A Wicking Bed, or Sub-Irrigated Raised Bed, is an extremely versatile, effective, and water-efficient food production system. You can build your own with a modest amount of carpentry skills in less than a day, and when finished will be a long-term investment, lasting for many years. Their greatest benefits are that they are self-sustaining, self-regulating, and can be adapted to use the most basic components. Other adjustments and design elements can be added or modified to change how the beds look or work.
Overall, wicking beds can improve yields in urban gardens, they can extend the growing season by warming up quicker in the spring, and you can attach a cold frame to them. They reduce water waste by preventing most evaporation, meaning there is no risk of salt accumulation, which will improve the long-term quality of your plants. They also provide automatic drainage in the event of a large downpour, and you can even automate the watering process using an intermediary tank. Wicking beds can even be nested together in a series, connected to each other via their overflow spouts, and set on a slope so that gravity automatically refills the wicking beds below as the ones above overflow with water. When it rains, water will also seep through the soil and gravel, adding a large volume of water and filling up the reservoir.
Even without an automatic watering system, a full wicking bed should be able to irrigate itself for days before needing to be refilled. And once it’s full, you will only have to refill it about once a week in the summer, and maybe once every two or three weeks in the spring or fall. This makes wicking beds great for community gardens, as they cut down on maintenance and watering.
How Wicking Beds Work
A wicking bed is a barrel, drum, or garden bed with a dual-chambered unit, or an upper- and a lower-chamber. The chambers can be made from a single container separated into two units, or from two independent containers stacked on top of each other and nested into a single unit.
When choosing what to use in the construction of the system, you can use just about any material, like plastic, wood, metal, brick, a bathtub, or even stacked tires, so long as it is food-safe, can hold soil and plants in the top, and retain water in the bottom. If the container is not food-safe or water tight, a plastic liner can be added on the inside to protect the plants and stop leaks in the reservoir.
Wicking Beds use two principles that, individually, are not unique, but in combination create an altogether new technique that makes for an incredible crop-producing system. These concepts are self-watering and self-feeding. Self-watering is achieved by the working of the two chambers in unison, with one chamber holding a reservoir and the other holding the plants. The reservoir section holds a large amount of water that absorbs up into the soil in the upper-chamber through a wick, causing it to become saturated, and the plants automatically draw water up to hydrate themselves until the reservoir is completely empty. This makes the best use of water that is available by watering from the bottom to prevent evaporation of surface water. Self-feeding is achieved through the use of a worm compost bin, installed directly inside the soil section of the bed, which can be used to recycle kitchen scraps, automatically replenishing nutrients in the soil. This will give you strong plants that have constant access to both food and water.
The lower chamber is a water-tight section that acts as a reservoir, while the upper-chamber (where the plants reside) is filled with a fertile potting soil mix. Water, given by hand or drip irrigation, percolates down through the soil in the top section, and drains into the lower-chamber to fill the reservoir. Water can also be poured directly down a dedicated watering tube or worm tower. As water is added from the top, it drains down through the bottom of the upper-chamber down to the lower-chamber, either through a water-permeable layer, or through drains installed in the bulkhead of the upper-chamber.
Below the soil is a wicking layer, made from a water-absorbing material, that extends down from the top section all the way to the bottom of the reservoir. When one end of the wick is saturated and the other end is dry, it creates a moisture gradient that causes water to move into the dry sections. The wick makes contact with water, and moisture quickly absorbs into the material. Moisture then travels up the wick by capillary action to the top chamber until the moisture gradient no longer exists, and the soil is fully saturated. As the plants use up the water, the soil dries out, and recreates this moisture gradient, driving more water back up through the wick. This way, water will automatically saturate the soil until the reservoir runs out of water. Over time, the plants’ roots will eventually grow downward to find the moisture in the base of the upper chamber.
Inside of the bed, you can also set up a worm composting system, built out of a cylindrical tube or chute, like a wide PVC pipe section. Cut a series of perforations or holes in the walls of this tube, drilled all around its sides along one-half or one-third of the cylinder. Then, place the worm farm directly into the soil. Make sure it is set standing vertically in the top section, with the holes buried under the soil, and the uncut side sticking out the top of the chamber. Food scraps are then added to the hollow, inner section of the tube. This way, worms living in the soil can enter the pipe through the holes, eat the food inside, and then move out back into the soil to deposit their castings. This will create fertilizer, and redistribute nutrients from the food scraps to the plants in the bed.
- Collard Greens
- Purple String Bean
- Sweet potato
Growing on a patio is great for tomatoes and other climbing plants, as the hand railing will provide a great lattice for them to grow on. If growing tomatoes, try painting your hand railing a bright, reflective red color, as this will make them ripen more. Place your unit on the north end of your patio, with no obstructions covering it from the south, to get the most sun throughout the day. Use plastic forks or knives as row markers to identify what plants you’re growing.
Despite their many benefits, wicking beds do have some flaws or disadvantages which could cause them to fail. The main issues regarding wicking bends tend to be sevenfold: 1) The wick degrades over time; 2) Fruit flies get into the feeding tube; 3) Mosquitoes invade the water reservoir; 4) Rodents dig into the soil, killing the plants; 5) The container freezes and thaws in the off-seasons; 6) Compost worms don’t survive the winter; and 7) The soil loses fertility over time.
Firstly, natural fabrics will decompose some weeks or months after installation. So, if you’re using a fabric based wick, and it has deteriorated to the point when it no longer absorbs water, then simply replace the wicks made from natural materials with some synthetic ones. This may require you to tear apart the unit completely, however, and should be avoided in the beginning. If your wick consists of a media layer, like sand or soil, then something may have happened to make it lose contact with either the top- or lower-sections. If this is the case, then you may have to take apart the bed and rebuild the wick or reservoir section.
Secondly, to stop fruit flies from getting into the compost, simply add a lid to the feeding tube, and keep it covered when it’s not in use. Every time you add more food to the pipe, top it off with some wood chips or shredded cardboard to keep out the flies.
As for the third issue, to stop mosquitoes from getting into the water and turning it into a breeding ground, add a cover to the dedicated watering tube, like a halved plastic water bottle, to keep it sealed when not in use. Also, be sure to cover the drain spout with a shade cloth or screen to keep pests from entering the reservoir.
Fourthly, to prevent rodents from digging, try designing the compost tube so that the holes drilled in the sides are set further down on the pipe, and are buried more deeply under the soil. At this depth, the rats will not be able to smell the food, so they won’t try to dig for it. You can also insert some wooden or metal skewers around the edges of the planting area, going down through the soil, to create a barrier to keep rats from digging at the plants.
Fifthly, to account for freeze/thaw issues in cold climates, drill an additional hole at the bottom of the bed and install an elbow and a faucet or spigot on the outside. This way, you can control the amount of water held in the bed and drain it before winter. Use recessed beds to prevent frost from developing in cold or temperate climate. They are particularly useful for this because the soil acts as insulation, adding a heat-sink around the water that retains warmth and keeps it from freezing.
Sixth, most wrigglers may not be able to survive cold winters. To keep the worms from dying, try having an indoor worm system ready when it starts getting cold out, so you can bring them in and keep them alive until the next growing season.
Lastly, grow nitrogen fixing legumes (in addition to your regular crops) to fix carbon and nitrogen into the soil and prevent it from getting barren. Also, make good use of compost and a worm farm to regularly add nutrients into the soil.
Parts of a Wicking Bed
The design of your wicking beds can be adjusted according to your budget, materials, space, and garden plan, but generally, most Wicking Beds follow a basic plan, containing several sections that work together in unison to create a well-functioning, self-watering planter.
Part A: Lower-containment unit
This is a lower-section with a level, flat-bottomed base, forming the waterproof membrane that holds the reservoir. It consists of everything below the soil zone, which separates the lower- and upper-units, including any materials needed for a solid support structure to hold the weight of the water, soil, and plants. This lower zone is made from a water-tight container or lining, like poly liner (e.g. builder’s plastic), a pond liner, or a hard, solid container inserted into the lower-part of the unit.
If your bed is built from a water permeable material (like wood, brick, stone), or if it’s buried into the ground, then you will have to seal it up by lining it with a water-tight membrane so that it will not leak. To achieve this, you can use a thick plastic sheet, 6 mil in thickness or more. A better liner to use would be a 10 mil vapor barrier, or 200 um builder’s plastic, which will hold up longer and better than the 6 mil liner. The best, but more expensive, option is to use a heavy duty, fish-safe PVC pond liner. Agricultural plastic has been used with success, as well as HDX clear plastic sheeting, but any waterproof material will work. Before installing the liner, first ensure there are no nicks, cuts, or holes in it that could cause leaks. If you are using solid, waterproof containers (like ones made from plastic, metal, glass, or fiberglass) then the addition of this plastic liner would be unnecessary.
First consider what building materials you will use. Do you want to use plastic, wood, metal, brick, or a composite of materials? Many cheap, recycled containers can be used, like plastic bottles, jugs, totes, barrels, and bins, or even metal buckets, Styrofoam boxes, round galvanized culvert rings, stock watering tanks, IBC containers, kiddie pools, wood or brick planters, bathtubs, etc. You can use almost any kind of container, as long as it can provide enough structural support, is deep enough to hold enough soil and water, and can be made waterproof. For example, you could use a salvaged freezer from the dump (after the Freon and mechanicals parts are removed) to make for a whole unit, sufficient to hold the reservoir and soil sections. Many other options could be suitable, but do not use any salvaged containers that once contained toxic chemicals, such as pesticides or petrochemicals.
Wicking Beds are different from most raised beds because you can use treated woods in your design. If using wood, most people use one of two options: either a treated wood, or an untreated wood made from cedar, redwood, or cypress wood. These are useful because they are naturally water resistant, and cedar even repels pests. Treated woods are also an option, since they are safe to use in these designs, as the lumber will be separated from the growing medium by an impermeable barrier made from plastic liner. This will create no risk of contamination by the chemicals in the wood.
Keep in mind that working with treated wood is a bit different from regular wood because the former doesn’t have as much dimensional stability as the latter, and so it tends to warp, bend, and twist more. For this reason, it’s best to not store treated wood for a long time, and to use it as soon as you buy it, sparing no time between when you bring it home and when you’re ready to build. Look carefully when picking them out at the store to find the straightest pieces. But be warned that, even after you bring it home, it may look different than when you bought it. Also be aware of any stamps or markings visible on the outside of the boards. Usually these may only be on one side, and you can orient the boards so that the sides with the most markings are put on the inside of the box and are not visible. In addition, it’s possible that if you’re using limestone bricks in your planter walls, then the bricks could leach out into the water to make it too alkaline. To prevent this, you may have to change out the bricks you’re using for the walls.
Once you’ve found the proper lower-containment unit, you’ll have to determine how big you want it to be. Many designs are between 16 ½- to 24-inches deep, including both the upper- and lower-chambers. The individual chambers should be between 12 to 30 cm deep, or about 5- to 12-inches. You can increase or decrease that depth, within reason, but don’t make it too shallow, as this will make the potting mix more saturated. This is because the perched water table doesn’t extend very far, making the mix more saturated as less soil holds the same amount of water. This extra saturation makes it harder for the plants to grow. Also, try not to increase the depth of the lower-section to more than 30 cm tall, as at that depth the water will struggle to climb up to the top. Any higher than 30 cm and the capillary action won’t be as effective.
- Water-permeable barrier (optional)
This is placed on the bottom of the bed, between the reservoir and the lower-containment unit, to protect the poly from punctures, if needed. The barrier can be made from landscape fabric, a burlap sack, weed mat, agricultural sheet, or other material. Line it up the sides and staple it to the inside of the walls. This may be unnecessary if using a hard plastic container, or if not using gravel or sharp objects in the reservoir.
- Reservoir zone
After creating an appropriate, water-tight containment unit, you need to make an empty void to hold the water that will raise the height of the upper-container, and also support the weight of the soil above. Inside of the lower-unit, add a hollow or porous object that raises the height of the upper-chamber without taking up too much space. This will create more void spaces, increasing the bed’s water holding capacity. Water will be stored within these voids, and slowly absorb upwards into the soil, saturating it evenly. The depth of this space should be between 15 to 20 cm, or a maximum of 30 cm, although this depends on the depth of the total bed and the frequency of watering. This will allow the second chamber to stand higher up above the lower-section, increasing the volume of water held in the reservoir. The objects or media layers you use will be a main factor in determining the depth of your grow space and the design of the reservoir.
Most designs use a solid support medium that fills the reservoir. Gravel is the most common medium because it is a cheap and easily obtainable way to allow easy water distribution. It can also hold a significant amount of water, and it simultaneously provides structural support for the upper-section. Gravel has about 33% pore space, which means that 1 cubic meter of gravel in a container will have enough room to hold 333 liters of water. Other materials could also do the trick, like crushed glass, blue metal, stones, broken bricks, river sand, coarse mulch, branches, or upside-down pots. However, don’t use lava rock as it’s too dusty and has sharp edges which could puncture the plastic liner, if you have one.
Instead of a media-filled reservoir, or in addition to it, another option is to use a large, hollow object to create more voids to hold the water, to raise the height of the upper section, and to provide structural support for the upper-chamber. Some good items to use are plastic milk crates, which are strong, lightweight, and don’t take up much space, leaving most of it open to be taken up by the water. Other options include plastic buckets or crates, recycled food containers, yogurt or cottage cheese bins, plastic cups, concrete cinderblocks, etc.
Many designs use a 4-inch wide corrugated drain pipe, also called weeping tile, buried in or underneath the media. This pipe is useful because it is hollow, with a large void on the inside, allowing it to retain a larger volume of water, and can be used with or without the gravel. Water is stored inside this tube, providing a large reservoir that will slowly be taken up by the plants. It also has slots, perforations, or holes cut in them along the sides to allow water to flow in and out of the tube. If your pipe does not have any holes cut in them already, simply make some small holes along the pipe’s length with a drill or box cutter. This increases both the water retention and the rate at which the gravel in the bed disperses water. However, weeping tile is not strong enough to support the soil on top of it, so you will need to add raisers to hold its weight up above the weeping tile.
People usually put some kind of fabric over the corrugated drain pipes to keep them from filling up with soil, but this isn’t really necessary, as some reports of years-long test trials without the fabric have shown that even though the corrugated pipes are exposed to the soil, they still don’t get filled up with very much soot, so wrapping them doesn’t seem to be necessary. However, if you want to wrap the black corrugated pipe with something, first choose the material you want (like synthetic landscape fabric), cut the fabric to length, wrap it around the pipe, and secure it with duct tape or zip-ties. Be sure to wrap the ends of the tube with the fabric, going around and securing it with tape (or tying it off with string or twine), to keep sand and dirt from entering. Or, you could cover it at the ends to make a cap screen, instead. You could also lay the fabric over the drain pipes, using it as the Reservoir/Soil-Interface mat.
- Wicking material
The unit works by utilizing a property of water, called capillary action, that causes moisture to flow upwards by absorbing, or “wicking,” into a surface or narrow space. When this water sticks to a surface, moisture will move from an area of high-moisture content into an area of low-moisture content by absorbing through that surface. In order for this wicking action to take place, there must be a mass of some kind of material, called the wick, that absorbs water from the reservoir and wets the soil in the upper-container. The wick can be made from a variety of substances, like cotton, wool, geo-textile, fabrics, soil, sand, or even wood. Every material has different wicking properties. To test a material’s wicking ability, place it into a glass of water and watch to see if the water climbs up it. Most designs use a media layer that consists of a column, or series of columns, of sand or soil that connects the top and lower chambers together. These are useful because they are cheap, easy to acquire and work with, and they don’t deteriorate over time.
You could also use a piece of fabric to act as your wick, but avoid natural fabrics as they will deteriorate and quickly lose their wicking capacities. Generally, when using a fabric wick, synthetic materials are preferable to natural ones because they deteriorate more slowly. A ¼-inch thick cord of polypropylene will make a good wick as it is affordable, lightweight, chemical resistant, and mildew and rot resistant. Although, polypropylene is susceptible to deterioration by UV radiation, but in this system it will be stored away from direct sunlight, which will extend its lifespan indefinitely. Nylon rope is also useful, as it is not damaged by most chemicals, has good resistance to sunlight, and resists rot and mildew. Polyester rope is equally resistant to moisture and chemicals as nylon, but is superior in resistance to sunlight.
- False bottom (optional)
Beds without a solid media layer in the reservoir will usually require a false bottom to suspend the soil above the lower-chamber and to keep it from intermixing with the water. This false bottom is a solid, hard layer, or a perforated platform (like a piece of metal, wood, or plastic with many holes or pores cut into it), placed above the reservoir, below the Reservoir/Soil-Interface mat and the Intermediary Sand Layer. This is meant to support the weight of the soil, but also allow water to pass through. For this false bottom, you can use a wire mesh screen, like some vinyl covered fencing material, or some other solid material, like a wooden board or a thin layer of plastic (like a cut-out piece of a plastic lid) with holes drilled through it.
- Overflow pipe
The overflow pipe is a necessary element in every wicking bed, as it allows excess water to be deposited outside of and away from the bed. This will stop overflows and prevent the bed from getting oversaturated. Under the spout of this overflow pipe you could plant a hearty herb, like rosemary, which will automatically get watered as the reservoir overflows and spills out of the valve. Or, set your beds on an incline and connect them together via the overflow valves to facilitate easy, automatic watering.
This is placed at or near the top of the reservoir, or at the level of the false bottom, and installed through the side of the bed above ground. As water flows into the fill pipe, or down through the upper-chamber, the reservoir in the bed fills up. Once the reservoir fills to the brim, and the water reaches the top of the media, it will flow out through the pipe, providing automatic drainage. This ensures the bed will not overflow during a storm. This way, the water level will only get to the height of the overflow valve, which defines the fill-line, and then drain out on its own. You can also use it as a visual indicator to show when the reservoir is full when watering.
The overflow spout can be installed in a number of ways, and some designs have their own, unique version. Although, most versions use some form of screen or barrier — like a piece of shade cloth wrapped over a plastic, rubber, or PVC pipe — to prevent blockages and to keep pests from entering the system. Other materials could be used, like metal, bamboo, wood, etc. If you have torrential downpours, your overflow holes may not be large enough to handle the flow capacity of the water. You can add extra drainage holes to protect against torrential downpours by simply drilling some holes, about ½-inch wide or so, into the sides of the container above the primary drainage pipe.
- Reservoir/Soil Interface mat (optional)
This is a water permeable barrier placed between the reservoir and the soil or sand. This is optional, but is meant to prevent soil from migrating down into the reservoir. This can be made from a wicking fabric or other water-absorbent material, like landscape fabric, geotextile, weed mat, a burlap sack, used bed sheets, an agricultural sheet, a shade cloth, or even some strategically placed plastic bags. This is placed on top of the reservoir to segregate the soil and sand in the upper-chamber from the lower-chamber, while preserving the pore space in the reservoir. This breaks the surface tension of the water, allowing water to wick upwards more easily. It will also act as a filter between the sand and soil, or between them and the reservoir, stopping them from intermixing.
- Intermediary Sand Layer (optional)
This goes over the top of the shade cloth or mat covering the reservoir, and is about 4- or 5-inches thick. This layer of sand helps the water to wick upwards, it keeps the soil from washing down into the reservoir, and prevents the soil from getting in the reservoir and causing anaerobic rotting. Make sure the sand you use is clean, and doesn’t get mixed up with organic matter. This is because the sand is for drainage, and you don’t want it to get clogged up with other materials. For best results, use some washed river sand. You could also use a layer of coarse gravel, or another material like wood chips, although sand is commonly used because it’s half the price of gravel.
In smaller designs of the wicking bed, like ones using plastic water bottles or jugs, there may not be enough available vertical space in the containment unit to fit the sand, so only (or mostly) soil will be used, instead.
- Mulch Layer (optional)
Put an additional layer of straw or sugarcane mulch, about 3- or 4-inches thick, on top of the sand to create a barrier between it and soil. This layer of mulch serves to further prevent the dirt from mingling with the sand, and it will compress down and make a thick, black, compostable layer. This way, if you ever need to disassemble the barrel, then you can just peel the soil right off the sand. The mulch also takes a long time to break down, and the worms will eat it as it decomposes. Instead of mulch, you could also use a shade cloth, weed mat, or a geotextile, although the worms will not be able to eat those.
Part B: Upper-containment unit
This holds the soil above the reservoir, and consists of everything from the bottom of the soil level and above. This part of the system may have several layers of sand and soil. This should be about 30 cm deep or more, although it can be less if you’re using a shallower container. It is important that the soil layer stay between 30–32 cm, or about 12-inches, or else the soil may not be able to completely wick up all the moisture. Water generally won’t wick past 18-inches, so you don’t want your soil to be any deeper than that.
The measurements can vary according to your needs and available supplies, and a container about 30-inches deep (with about 14 inches for the top section and 26 inches for the reservoir) could work. If the upper-section is too deep, then the soil at the top will likely be much drier than the lower soil. In this case, make sure that the plants you use have deeper roots so they can access this moisture. Try using tomatoes or root vegetables, which can be buried deep into the bed.
- Soil zone
This is where the plants grow, inside a fertile, nutrient-rich potting base mixed with organic ingredients. Use compost and other organic nutrients made from good quality, organic soil or potting mix to make a rich growing medium. However, don’t use pure manure, bagged compost, or lots of grass composts in the soil.
Whatever you fill the bed with, build it using a potting mix base. This will improve its wicking capabilities to draw up more moisture from the reservoir, and give you nice pore spacing to increase aeration and prevent root rot. You can use worm castings, which work great in containers, or organic fertilizers and time-release fertilizers. You can optionally put a 1-inch wide ring of the granular fertilizer on the surface around the plants. Simply spread the appropriate amount of the fertilizer around the plants in a ring, mix it in evenly, and cover it with a bit of top soil.
The best soils are made from a premium, lightweight, pre-made mix, while adding some extra nutrients to increase fertility. Consider using a mix that has more sand or other aggregate (e.g. pine bark, mulch, perlite, etc.) mixed in it than organic matter. The reason for this is because if it’s too full of organic matter, then it may compact over time and not drain freely enough, causing the water to stagnate. With lots of sand, structure is added to the soil, allowing the water to circulate and drain more freely. Don’t use too much regular soil, as this won’t be able to wick moisture as well.
Also, you can try adding 1 ½ cubic feet of pine bark mulch and 2 gallons of perlite, or a roughly equal amount of sand. This will add extra aggregate and coarse, fine particles for aeration, and also increase the volume of your mix so that you use less soil. The wood mulch also takes a long time to break down, extending the lifespan of your mix. If using other woods in your compost, make sure you use untreated wood and saw dust, as the treated varieties use formaldehyde and other toxic chemicals that will leach into the soil. However, if you’re using mostly pine bark or peat moss, then you’ll need to add something with extra nutrients. To add extra fertilizer, you could add some Dolomitic Lime, which is made of calcium and magnesium, and would be useful when using a synthetic potting mix like Miracle-Gro.
To prepare the soil, get one 2 cubic foot bag each of moisture control and regular Miracle-Gro potting mix. Mix this all together in a tarp or large bucket. To keep up soil fertility, use a cover cropping or make an addition of compost, blood and bone, and Rockdust. Good soils would include about 2 bags of compost and worm castings. Or, you could use pure compost mixed in with some topsoil.
To create your own potting mix using a mixture of topsoil, take some of the soil that came out of the bed originally, and filter it through a screen to break it up and aerate it. Then make a 50/50 mix with mushroom compost and cow, horse, and chicken manure, blended evenly with the soil, and add some worm castings and a few handfuls of composting worms. To this you can also add a little bit of rock phosphate, Greensand or Kelp Meal, and Blood meal. You can also use a combination of loam, compost and peat, or even a mix of pure vermiculite or peat moss. In that case, put in one part peat moss, one part vermiculite, and one part worm castings, and blend in some fertilizer, manure, blood and bone, Rockdust, worm castings, and compost into the original soil. This will make a biologically active, nutrient-rich potting soil. If you intend to add some composting tubes, then reduce the amount of mushroom compost you add to the soil.
- Fill pipe (optional)
This is a vertically-standing tube, placed in one corner or on one side of the bed, to be used to fill the reservoir with water. This may not be needed for small beds, barrels, or pots, and could be substituted with composting tubes.
For the fill pipe, you can use any waterproof tube, such as the weeping tile used in the reservoir, a separate PVC pipe, or even plastic bottles stacked together. Cut the pipe to an appropriate length, or about two to three feet long, depending on the height of your beds, so that it is long enough to reach all the way down through the top chamber and into the reservoir, with the top edge of it reaching a good deal above the surface of the soil. At the bottom end of the fill tube, cut an angled bevel to allow water to escape more easily. The fill tube should go straight down through the upper-chamber, sticking directly into the lower one, and reaching all the way to the reservoir. If using a rock or media layer in the reservoir, stick the fill pipe through the weed mat and into the rock base, resting it on the top surface of the gravel.
Once installed, this fill pipe allows you to fill the reservoir easily and quickly. Simply stick a garden hose into the tube, turn it on low- to medium-pressure, and fill it up until water leaks out of the overflow valve. With this system, it could take several minutes to completely fill the reservoir. Lastly, cover the pipe with a cut-off piece of a plastic bottle, or another cover, to prevent insects and debris from getting inside. Inside the watering tube you can also set up an automatic watering system, using drip irrigation, which can keep the reservoir constantly filled to a depth of about 1-inch below the fill line to prevent storm overflows.
- Worm composting bin (optional)
One popular tweak is to insert a worm composting tube into the soil portion of the bed. Food scraps can be added to the inside of the tube, and the worms will eat the food scraps and create castings. These castings provide fertilizer for the plants, which the worms will distribute throughout the bed, keeping the nutrient levels in the soil high. The worms also help to keep the system aerated and therefore prevent it from going anaerobic. The worm farm could also double as the fill pipe, if needed.
- Mulch and woodchips (optional)
Cover the topsoil with an additional 1-inch thick layer of woodchips, Lucerne hay, or mulch to keep the top of the beds moist, to protect the surface, prevent evaporation, and to stop local cats and other animals from using the beds as toilets. Using a cover cropping also reduces weeds, shades the soil, and provides a built-in mulch system.
- The plants
When you’re ready to plant, choose your location for each seedling, and move the woodchips and mulch over to expose the soil under it. Add the transplants, and move the woodchips back into place. After planting, water directly on the surface for the first few days to allow their roots to grow. Once the plants are established, they will benefit more from being watered via their roots from below. You can put the unit up against a wall, and add a wooden trellis or netting behind it to make a space for climbing plants to grow. Put tall plants in the back, up against the trellis, with the shorter plants at the front.
Fill the reservoir with water, and re-fill every two to four weeks. During summer, top them off with water once every week, but every winter, they will only need refilling every 1 1/2 to 2 weeks. It’s also a good idea generally to add a bit of water to the top-soil every week or so, watering from the top down. This helps the surface roots and gives you an opportunity to add a liquid plant food, using a Sea Salt, Seaweed fertilizer, Fish emulsion, or Compost Tea.
There are about three different techniques, or design options, for building wicking beds:
- The kind that is built from hard plastic containers, like the global bucket or earth box, using a food-grade plastic tote.
- The kind that is built using a box frame, usually from wood or another material, and is similar to a raised bed, sitting directly on the top-soil, or on raised stilts about 2- to 3-feet up in the air.
- The kind that is partially buried in the ground, with a trench dug under the surface acting as the reservoir, or part of the reservoir.
Common Tools Used
- Power drill
- Hole saw or straight blade
- Jigsaw or Saber saw
- Table saw
- Plastic zip-ties
- Tape measure
- Knife or box cutter
- Felco pruners
- Magic Marker
Design 1a: Single Tote Earth Box using plastic water jugs
This design uses just one large, Rubbermaid container. The reservoir can be done in either of several ways. The first method uses three 2 ½ gallon plastic water jugs.
Start by cutting off the bottom of your water jugs to give them a flat bottom, and cut or drill some additional holes through their sides. If you want greater water retention, and thus a larger reservoir, then cut off less from the bottom. If you want a smaller reservoir, then cut off more. If you’re growing in a drier climate, or growing more water-loving crops, then you’ll want to have a larger reservoir, and to cut off less.
Next, make an overfill hole to drain out the water at the maximum height of the reservoir. This will set the maximum water level, or the fill level. To hold as much water in the reservoir as possible, place the hole at the top of the reservoir, just below the lid that sits on the soil. Figure out how high your reservoir reaches, and drill a ¼-inch overflow hole in the side of the tote box, right at the maximum height of your reservoir. This acts as both a drain, as well as a fill-spout, which you can use to water the unit in case it gets dry. You can also water from the top, pouring directly on the soil and plants. In case of high storm events, which can rapidly add a large volume of water to the bed, consider making the drainage hole larger, or drill additional holes.
Next, get three regular plastic, disposable water bottles, and cut off the bottom ends so you can put them inside each other to make a stacked column. Cut a round hole into one of the large water jugs forming the reservoir, and stick the column of water bottles in the hole. Insert the spout of the bottle, at the bottom of the column, directly into the jug through the hole you cut in it earlier. Be sure the wider, open end of the column is sticking out and up. This will act as the fill tube, allowing you to easily fill the reservoir. You could also use any reasonably sized piece of PVC tubing, cut to the appropriate length.
Next, use the container’s lid to create a hard, plastic barrier to support the soil. Start by drilling pilot holes in each of the corners, aligning them around the rim of the lid, near the corners and flat on top in the center. And, then cut along the edges with a sharp knife or box cutter, going straight from one hole to the next, but leaving the outer section so that it can be fastened on and off. Try to size the cut correctly so that it fits inside the tub, resting neatly over the bins. But make sure you leave a little bit of an edge left on the cut-out section of the lid, so that it pushes against the sides and makes a more secure barrier against the soil.
After cutting out the lid, you need to cut some holes in it to provide an entrance for the wick that will suck the water up to the plants. Put the lid in the tub, and mark where you want to locate the wicks, which, in this design, could be made from a synthetic fabric. Cut out two or three holes in the lid (sized according to the thickness of the ropes, maybe ¼- or ½-inches), to act as entrances for the wick, and put the wicks through the holes. Then lay down some agricultural fabric over it, and add sand and soil, watering lightly as you go. You want to have between 8 to 10 inches of soil depth. This will give you ample room to grow most crops. If you have smaller tote containers, then you can cut the jugs down the middle along the seam to make them shallower.
The above design can also be redone using weeping tile instead of the flower pots to create the reservoir. Other details in the construction are similar to the ones above.
Design 1b: Single Tote Earth Box using flower pots
The other method is very similar to the one above, but it uses six to eight 1-gallon plastic bins, made from large yogurt containers or plastic flower pots. The yogurt containers are shorter than the flower pots, and thus will give you a smaller reservoir but a deeper soil depth. This would be good to use for plants that need less water, or for plants that need more soil to grow, like root crops. Drill or cut some small holes in the sides and bottoms of the containers, if they don’t already have some, so that water can pass through them easily.
Then, fill the large container with the yogurt bins or flower pots, turned right-side up so that their open ends are pointing up to the sky. Simply line them on the bottom of the container, fitting in as many as possible without overfilling it. Just at the top of the reservoir, drill a hole about ¼-inch in size through the side of the container to act as an overflow drain.
You can create a wick by filling up one or two of the flower pots or yogurt bins with sand or soil, which will then suck the water up into the dry soil above. Place the lid on top, making a plastic screen separating the upper- and lower-containers. Then, mark where you want to add the soil, and cut out two or three holes big enough to allow you to reach down into the reservoir. Cut out a piece of a large shade cloth, or agricultural cloth, big enough to fit inside the pots and cover the plastic lid. Then, lay it over the opening of the flower pot, lining it along the bottom, and it fill up with sand or soil. Pack it in well to ensure adequate contact between the upper- and lower-layers.
If you don’t want to use soil as your wick, you could instead use some synthetic fabric or rope hanging down from the top and resting at the bottom. Just adjust the size of the holes you drill into the screen between the units to compensate for their decreased width, as the holes would then only need to be the same size as the thickness of the fabric itself.
Design 1c: Single Tote Earth Box using plastic cups
- 1x 18-gallon plastic bin with lid
- 2x 16 oz. plastic cups
- 1x length of 4-inch wide PVC pipe
- 1x 2-3 ft. long PVC or plastic pipe
Take the plastic tub, and cut away the center of the lid with a saber saw, but keep the remaining rim for later. The cut-out portion of the lid should be sized just right so that it fits inside the bin to create a screen or false bottom that will hold the soil above the reservoir. Then use the saber saw to cut out two large holes in the lid on the sides, big enough to fit the plastic cups, and perforate it with holes using a ¼-inch drill bit.
Cut three sections of a 4-inch wide PVC pipe with a table saw so that each one is about 5 ¼-inches long, or the same length as the height of the plastic 16 oz. cups. Drill several holes in the sides and the bottom of the PVC sections, and the plastic cups, using a 1/8-inch drill bit. The cups are used as wicking baskets to fill with wet soil or sand, so that water will wick up to the soil. Set the three sections of PVC in a triangular formation on the bottom of the bin to provide structural support. The screen, or the cut out portion of the lid, sits on top of these PVC columns, 5 ¼-inches above the bottom of the bin.
Use a 1 3/8-inch drill bit to cut a hole on one side of the screen. This is used to allow an entry for the watering pipe, used to fill the reservoir. For the watering pipe, take any suitably sized plastic or PVC pipe, about 2- or 3-feet long, and cut off the bottom 1- or 2-inches with a hacksaw at an angle to allow water to flow out. Next, mark spots on the side of the bin to attach a cable tie, and use a 1/8-inch drill bit to create the holes. Once that is done, secure the watering pipe to the walls of the bin with a cable tie, and snip off the extra bits of plastic from the tie with wire cutters or scissors. Use a sharp knife or box cutter to cut a notch in the rim of the lid to fit the watering pipe. The rim can also be used to secure a plastic sheet on top for mulch.
Next, mark a spot for an overflow drain hole on the side of the tub, just above the screen (or at about 5 ¼-inches above the bottom of the bin), and drill a hole using a 3/8-inch drill bit. Inside this, you could insert a pipe with a shade cloth wrapped over one end to make an overflow spout.
Lastly, fill the cups with potting mix or sand, and insert them through the screen inside the bin. Saturate them with water, and cover them with a couple inches of sand. Then, fill the rest of the bin with potting soil, watering as you go, and add the plants.
Design 1d: Dual Tote Earth Box using milk crates
In this design, two large Rubbermaid storage bins are used to make two units stacked on top of each other. The soil is suspended in the upper-chamber with wicks dangling into the lower- one. This design is useful for plastic totes and containers, and can be made with a single or double-unit system.
For a double-unit system, get the following supplies:
- 2x Large (37 gallons or more) Rubbermaid storage boxes with lids
- 2x plastic, cube-shaped milk crates
- 1x 2-foot long, 6-inch wide PVC tube
- 2x plastic drainage baskets or cottage cheese tubs
- Agricultural cloth, burlap, or old cotton cloth
To start, select the container you will use as your upper-chamber. This will be the only container that you make any significant modifications to. Take the plastic drainage baskets, and lay them inside the tote, upside down. They should be placed opposite each other, and spaced equidistantly from the sides. If you can’t find these specific baskets, then you could substitute them with some large-sized plastic food tubs.
Set them in the spots you want them with the rims laying flat on the inside of the container, and mark a circle around their perimeter with a pen. Use a power drill to make some small holes on the inside of the lines marking the outside of the baskets, and then cut them out with a knife or box cutter. The perimeter of the circle made by the holes should be slightly smaller than the baskets themselves, but be big enough to fit them neatly inside. Their rims should catch onto the sides so that it dangles out the bottom, but does not fall through. After cutting out the holes, test the fit with the plastic baskets, and remove them for the next part.
Next, choose the wicks you will use, preferably a cord of synthetic rope. The wicking rope should be long enough to extend from the top chamber all the way down to the bottom of the lower chamber, with one-third of the length of the rope going into the water, and the other two-thirds rising up into the soil. This will ensure that all of the soil is properly moisturized. Alternatively, it could be laid down flat on the bottom of the bin, coiled into a spiral. Cut about a 10-foot length of rope, and fold the rope over itself into thirds.
Tie a stopper-knot at the one-third mark to prevent it from sliding through the grate of the basket and falling into the reservoir. Then take the basket, and feed the rope through the slots on the sides, or through the holes in the bottom. Put as many as two to four ropes through each basket. Once the ropes are in place, tie a figure-eight knot at both ends to keep them from fraying, and then lay some fabric down over the net baskets and secure them with a rubber band to prevent soil from falling down into the lower-chamber.
Now you can start assembling the bottom tote. Start with the lid, and invert it to make a stable base for the unit. Set it in place in a sunny spot flat on the ground, and put the bottom tote inside the lid. Then put the two milk crates together inside the bottom tote. If you try to add each one individually, you may find that they’re too big to fit them both. Instead, try to slip them in together at the same time, gently wiggling them in, and push them down as far as you can without splitting the sides of the tote. Make sure you orient the open sides of the milk crates upwards so that the drainage baskets will have room to fit inside.
Now, put the upper- and lower-totes together, setting the upper-chamber directly on the milk crates. Carefully lower the baskets into their holes, pushing the fabric wicks down inside. When the wicks are in place, carefully apply a bead of silicone around the edges of the holes, fit the baskets through the holes, and push them down to seal them together, wiggling them around a bit to get good contact. Apply extra silicone around the outer edge if needed, and allow them to dry.
Next, create a feeder tube for a worm farm to serve as a composting station in the upper-container. Constructing the composting station is the same for most designs. Simply get a 6-inch wide PVC pipe section cut to about 2-feet long. Start by marking out some indicator spots, or reference marks, around the circumference of the tube.
Space them out away from each other by about 2-, 3-, or 4-inches (depending on the sizes of the holes you will make), and going down along one-third or one-half of the tube. This is the part of the tube that will go down under the soil. The holes should be buried deep enough underground so that the rats can’t smell the food, but not so deep that the worms will have trouble digging down to reach them.
Once all the spots have been marked, clamp the PVC pipe down to a work bench, and make some pilot holes at each reference point with a 1/8- or ¼-inch drill bit. After making the pilot holes, then finish them off with a larger bit, of about ¾-inches or wider. Making larger holes will give the worms more room to move freely, unimpeded by plant growth, food scraps, or other materials. After drilling the holes, there will probably be many sharp barbs hanging off of the PVC tube. Clean them off with a farmer’s sickle, or another piece of flat sharp metal, by scraping it along the sides as if you were shaving a leg.
Before filling the upper-chamber with soil, first put some more fabric down inside the baskets to fill up the empty spaces. Then lay another piece of fabric over the tops of both baskets, and wrap a rubber band around the seal to secure them. This will add another barrier to keep soil from falling through. When you’re ready to fill it with soil, put the feeder tube or worm farm down into the middle of the unit, right between the two drains on the sides, resting it on the bottom of the upper-unit. This way, both sides of the unit will receive nutrients from the worms and compost equally. With the tube in place, fill the bottom of the upper tote with woodchips or sand, going up by a few inches, or enough to cover both drains. Water the sand or woodchips a bit, and then add layers of soil, watering as you go. Keep on adding more soil and water until you fill up the upper tote. Leave an inch or two of space between the top of the upper tote and the soil level for mulch.
If using a dual-unit, like in the double-tote design, there may be water exposed at the surface of the reservoir, and mosquitoes could get in the water through here and spoil the system. To prevent this, add some aquatic plants around the edges so that there’s no space for the mosquitoes to drop their eggs and breed. The plants will grow in the water, eat up nutrients from the water around the edges, and block out light from getting into the reservoir, which prevents algae growth. Mosquito larvae normally grow by eating this algae, so by stopping it from growing, and removing the nutrients from the water with the plants, it removes all possible food sources and starves any insect larvae that could be living in there. In addition to being functional, the plants are also attractive-looking, appealing to the eye, and a nice way to decoratively adorn the unit.
To find the right plants, simply go down to a local creek or pond, walk along the edge of the water, and pull up any plants you see growing along the sides. Try picking a variety of plants with differently shaped leaves, like ones with rounded lobes, clover shapes, pointy leaves, and some with multiple edges and composite leaves.
Design 1e: Single 5-Gallon Bucket Earth Box using weeping tile
Get some 5-gallon buckets with lids, scissors, a sharpie marker, box cutters, a drill, ¼-inch drill bit, some corrugated drainage pipe, and some PVC pipe. To find the 5-gallon sized plastic buckets, try calling local bakeries, restaurants, or grocery stores. These businesses usually get their ingredients shipped in plastic buckets, only to be thrown away after one use. Instead of accumulating these buckets as garbage, they might be happy to give them away for free.
The first step in this process consists of making the wick and the Soil-Interface screen using the bucket’s lid to make a soil-screen, and a piece of corrugated drain pipe or weeping tile to hold the soil-sand wick in place. Take a piece of the corrugated pipe and cut it to your desired length, of 5- to 12-inches, depending on the needed size of your reservoir. Put one end of the pipe over the lid of the 5-gallon bucket, standing it upright, and mark around the outside of it with a sharpie marker. Drill holes into the lid, following the markings, going around the perimeter, so you can cut it out with a box cutter. Drill additional holes in the lid, going inside and around the large central circle for assisted drainage.
Next, scrape the box cutter around the inside edge of the circle you marked with a pen, and slowly cut out the hole, poking the knife through the lid as you go around. Once you get this done, take the circle that you just cut out, and squeeze it into one end of the corrugated pipe. This will form a solid bottom plate within the weeping tile to better hold the sand or soil, and to keep it from spilling out of the tube. This makes for a great wicking device to use in your reservoir.
Then cut out the rest of the lid with the box cutter to make a donut-shaped disc. Start by scraping a circle around the rim, but leaving about ½-inches or more on the sides, so that the rim can sit securely on the bucket, fitting snugly over the top like normal. Continue scraping around the perimeter a couple of times, enough to cut through one side of the lid. Then stick your fingers through the opening and pull it out to tear the inner portion of the lid right off. Then slip that over the top of your corrugated drain pipe. To secure this piece of the lid to the pipe, drill some small holes in the top of the corrugated pipe to add zip-ties later on. Then test the fit in the bucket by putting it inside, setting it down in the reservoir.
Next, insert the PVC fill pipe, standing it upright, and set it right on top of the lid connected to the corrugated pipe. Make a mark on the lid for where you want it to be located, preferably touching the side of the bucket. Cut this hole with scissors or a holesaw, insert the pipe, and put the wick and screen assemblage in the bucket. Then add the potting mix.
Design 1f: Dual 5-Gallon Bucket Earth Box using a plastic food container
You could also use an Earth bucket style system, which consists of a large plastic bucket that has multiple small holes drilled on the bottom, and placed over an unmodified bucket.
- 1x 2-foot long, 1-inch wide PVC pipe
- 2x 5 gallon buckets
- 2x Large plastic shopping bags
- 1x 16 oz 3-inch plastic container
- 5x Rubber bands tied together, or 1x bungie cord
Get a 3-inch wide, 16 oz. plastic food tub, like the kind used to hold butter, sour cream, or cottage cheese. You can also use 3-inch net pots, plastic drinking cups, or even a flower pot. This food tub will hold a wicking substance, like sand or soil, and hangs down from the bottom of the upper bucket, reaching down into the reservoir. The water wicks up through this material, hits the bottom of the soil, and is absorbed by the plants. In this design, the short food tub makes for a smaller reservoir, but it could easily be expanded by using a bigger food tub, or weeping tile, and using PVC raisers to hold the soil.
Take two 5-gallon plastic buckets and choose one as the upper-containment unit, which will hold the soil. The other one will hold the reservoir, and will serve as the lower-containment unit. First, find out where the drainage hole will be in the lower-unit. Hold the bucket up to the light, and lay the food tub flat on the bottom of the inside of the bucket, and make a mark on the outside with a marker right where the 3-inch plastic food tub meets the side. This will indicate the placement for your drainage hole, and should be about 3-inches above the bottom of the 5-gallon bucket. Drill a hole there with a ¼-inch drill bit.
Then take your drainage cup (the 3-inch wide plastic food tub), and drill some holes around it on the side and on the bottom with a ¼-inch drill bit. Then flip the 5-gallon bucket over, so the bottom side is facing upwards, and put the food tub flat on the bottom, upside down, directly in the center. Take the marker and mark all the way around the edge of the plastic tub to mark where the rim meets the bottom of the bucket. Drill some holes along the inside of the line marking this central circle, so that when you cut it out with a jigsaw, the final hole is slightly smaller than the diameter of the food tub. When finished, the tub should fit perfectly inside, with the lips fitting snugly on the sides.
Next, drill some holes into the bottom of the top-bucket with a ½-inch drill bit for drainage. Orient the holes so that they are grouped together in lines, radiating from the circle you marked on the bottom. Together, they should form a series of concentric circles around the hole for the wicking cup, emanating from the center in straight linear patterns, like gleaming sun beams.
Lastly you need to make a hole for your fill pipe. On one end of the pipe, cut it at an angle to let the water flow easily in and out. Then place this pipe where you want it, mark a circle on the bottom of the upper-bucket in the proper location, and cut this hole with a knife, straight blade, jigsaw, or a hole saw. Clean up the edges with a file, and test the fit by sliding it down into the reservoir.
Then flip the bucket over so it’s right side up, and put it down inside another bucket of the same size with one or several overflow holes drilled in the side. This second bucket holds the other one inside, acting as the lower-unit, and the space between them creates a reservoir for the water. Place the 3-inch plastic container down in the hole in the center to test the fit. It should reach down to the bottom of the lower-bucket, but should not get pushed up by the bottom because of a misfit. This serves as a wicking cup, and will be filled with a soil-sand media layer.
To create this wick, remove the wicking cup, lay some fabric over it to cover the inside, and fill it with potting mix, sand, or soil, packing it in tightly. This should create a barrier between the soil and the lower-bucket to keep soot and soil from falling through and filling the reservoir. Lay down some fabric along the bottom to further prevent soil from falling down. You could even use regular, large-sized plastic shopping bags, but just make sure they are big enough to cover the bottom of the bucket. Use a knife to perforate some holes in the bag to allow for extra drainage, and line it, or the fabric, on the bottom of the upper-bucket. The bag also should not cover the wick, so be sure to cut a hole in the bag, through which the water will pass. Simply cut an x into the center, insert the tub through it from the inside, and place it down on the bottom, fitting it into the bottom hole of the bucket. Lastly, insert the PVC watering pipe into the small hole on the side.
After finishing off the bottom and the reservoir, add a layer of sand to cover the drain by 3 to 4 cm, or 1 ¼- to 1 ½-inches. Flatten the sand, and add a 4-inch, or 10 cm, thick layer of straw or sugarcane mulch. Then, fill the rest of the bucket with potting mix, and add some compost and composting worms at the surface. Lastly, top it off with an inch or two of mulch, and add the plants. Water the surface lightly, and fill up the reservoir.
Design 1g: Drum Barrel Wicking Bed
Get a large waterproof barrel, like a 44- or 55-gallon drum (the blue or white kind), made from food-grade, molded plastic or high-density polyethylene. First, stand the barrel upright on the ground, and measure its height. Make a mark at the half way point with a magic marker, and make some reference marks every few inches all around the barrel, going in a circle around the outside, parallel with the bottom and top edges. Then, turn it over on its side, and lay a piece of wire or string across the marks, holding it taut, and draw a solid line over them all around to make a circle. Drill a pilot hole through the line, and then cut through the rest with a jigsaw, angle grinder, or hacksaw to divide the barrel in half. Scrape off any frayed pieces of plastic with a box cutter to clean up the edges.
An outlet pipe, consisting of a small tube with a screen over one end, allows the water from overflows to runoff in case it rains. It also lets you know when the reservoir section is full. One standardized overflow pipe, which you can construct yourself, uses some pre-fabricated plastic or rubber pieces, like a grommet and pipe joiner. These grommets could come in multiple sizes, like 13 mm, 16 mm, or 19 mm.
First, mark where you want the overflow hole to be located just below the top of the reservoir, which should be about 5-inches or between 10 to 13 cm from the bottom. Although, you could set it higher or lower if you want a differently sized reservoir. This will mark the maximum fill line, and give you about a foot of soil depth, or more, above the reservoir. Mark where you want the hole to be located, and drill a small pilot hole with a 1/8-inch or 3 mm drill bit. Then, finish it off by drilling a 5/8-inch or 16 mm hole, and clean up the sides with a utility knife.
For the drainage pipe, use a ½-inch or 13 mm wide plastic pipe or barb fitting, cut to about 3- or 4-inches long. Then wrap a shade cloth, fly screen, or any other lightly woven material around one end of it. Start by folding the bottom end around itself, and then wrap the layer over the top to make an S-shape. Lastly, put a zip-tie or twine around to secure it. Then, pop in a 5/8-inch top hat grommet into the drainage hole from the inside, and push the uncovered end of the overflow pipe through the hole, popping it in. Before inserting, try wetting the uncovered end of the pipe with a bit of water to lubricate it.
Instead of a grommet, you could also use a flexible pipe or hose, cut to the same length as the one above, or about 3- or 4-inches. Simply drill a hole in the container about 1 mm larger than the hose itself. Wrap some fly screen or shade cloth around the end of the pipe or hose, and push it through the hole by about an inch. The grommet, however, is more secure and permanent than this.
For the reservoir at the bottom of the barrel, use a long piece of a slotted, corrugated plastic drainage pipe or weeping tile. Loop it into a circle to make a donut shape, or in a spiral to make a coil, leaving enough room in the middle for the sand to fill in and create a wick. Put the weeping tile on the bottom, and cover it with a weed mat or a large sock to keep sand and soil from falling into the pipes.
The fill pipe can consist of one end of the weeping tile, zip tied to the top edge of a barrel through some holes drilled in the sides. Water will enter the fill pipe and slowly leak out the bottom. Instead of using the drainage pipe as a fill tube, you can instead get a thinner length of plastic tube, and insert it into the drainage tubing. At the uncovered end of the drainage pipe, cut a little hole at the top, shaped like a trap door, to put the fill tube inside. Simply cut out a rectangular shape, like a 3-sided square, and bend it upwards over itself to make an opening. Insert the beveled end of the fill tube into the hole, and pull the fabric around the drainage pipe to cover it at the end, stretching the fabric up and over the fill tube, and tie it off with a string or twine. To keep the fill tube secured to the side of the barrel, drill a small hole near the top rim of the barrel on either side of the tube, right where you want it to stand, and tie some zip-ties through the holes going around the tube.
Insert the drainage pipe into the bottom of the bed to create the reservoir. You can add gravel in the voids next to and around the weeping tile to create even more void spaces. Then, lay down some shade cloth over it, covering the top of the reservoir, to stop any sand or soil from getting into the weeping tile. Then fill the rest of the reservoir with sand, covering the drainage pipe by a few centimeters. You could also take smaller sections of the corrugated plastic drainage pipe, cut to about a foot long, and wrap them with shade cloth. Then, add them back into the wicking barrel at the bottom to increase the volume of the reservoir.
Alternatively, instead of using weeping tile, you can fill the reservoir with pebbles, rocks, or broken bricks, leaving an empty space in the middle for the wick. Use smooth rocks to prevent your liner from getting cut by sharp edges, or add some shade cloth over the liner to prevent punctures. After adding the rocks, cut out a piece of weed mat, or plastic sheet (like a simple garbage bag) big enough to cover the rocks, and sized to line the inside of a plastic flower pot, placed in the middle of the bed. Line the center of the weed mat or liner in the flower pot, and fill it with sand or soil. Put the pot at the bottom of the reservoir, in the center, with rock media or weeping tile surrounding it on the sides, and spread out the shade cloth over the rocks. This will provide a nice even column of sand, which the water can wick through and use to climb to the upper-chamber. Using this allows you to fill the reservoir with more media or weeping tile, without leaving a large indentation in the center that will be filled with sand, creating more voids to hold water, and thus making a larger reservoir.
When adding the sand, go around the outside first, keeping the weed cloth down. When the reservoir gets filled with water, it will pool inside the hollow center of the bed, in the center of the spiral. The sand will wick the water up into the soil above it. The drainage pipe should be covered with about 1- or 2-inches of sand above the fill line. This is to keep organic matter in the soil from sitting in water for a long time, which could create anaerobic spots, making the soil more acidic and creating bad smells. Then, level the sand so that it’s completely flat, and add about 10 cm, or 4-inches, of sugarcane mulch to create another barrier between the sand and soil, which adds additional protection to keep organic matter from getting into the water.
After wrapping the shade cloth around the drainage pipe, and adding it into the reservoir, then set the barrel on some bricks or a frame to set it high up off the ground. Make sure the barrel is level, and then add the sand. Fill the middle indentation with sand, and then push it out to the sides, completely covering the weeping tile on the bottom. Flatten the sand and level it off. Then, add a layer of sugarcane mulch, shade cloth, weed mat, or geotextile over the sand. At this stage, the distance between the top of the sand layer and the top rim of the barrel should be about 35 cm, or about 13.8-inches.
Next, fill the barrel with soil, add the plants, and cover them with mulch to prevent evaporation. When filling the barrel, you can add an extra 5 to 10 cm of soil on top of the barrel until it’s almost overflowing. After adding the soil, you can secure a wire mesh to the barrel to add a support for climbers by drilling some small holes along the top edge. Wrap the wire through the holes, and tie them together. If you plan to move the drum, you can also add some handles by drilling two small holes near the top rim on either side, and feeding in some rope through them. Insert a piece of rubber tubing over the rope to provide a soft grip, and tie the ends of the rope through the holes.
Design 2a: Square Wooden Planter Box
For this system, you have to construct a frame to hold the plants and reservoir. For the frames, you can use some regular two-by-sixes, stained or painted, and preferably pressure-treated to prevent rotting. Use them to make a square-shaped box that’s 4×4 feet square, made from three of the boards stacked on top of each other to create a flat wall on each side. Drill a hole about 1/2- to ¾-inches wide, or the same size as your drain pipe, into the side of one wall, just above the first plank on the bottom edge. This defines the fill-line. Through this you should insert a pipe to create a drain spout. Use a piece of plastic tubing or garden hose (which will last longer) as the overflow spout. This sticks out of the side, going over the top of the bottom-third of the box, which borders the top of the reservoir.
The water reservoir consists of an empty box lined with plastic, specifically a roll of HDX clear plastic sheeting, 10-feet wide by 25-feet long and 3.5 mil thick. This should be enough plastic to line about two of the square boxes, doubling it up so it’s a few layers thick. Fold the plastic in such a way that it completely covers the bottom of the box, and goes up the walls past the bottom third of the box. After lining the box, secure the sheeting to the walls with a staple gun, and tuck the top edge of it up and around the drain pipe. But, make sure you apply the staples above the overfill line so as to not compromise the lower-unit’s water retention capabilities.
Then, put in a corrugated, black plastic drainage pipe, or weeping tile for the reservoir. For each box, you will need a drain pipe of about 10-feet or more, coiling it around itself to make a spiral shape so that it lays flat on the bottom of the box. Next, get a piece of PVC pipe for the fill pipe, about 2-inches wide and about 2-feet long, and make an angled cut at one end. This part goes into one end of the weeping tile, through a hole cut into it with a utility knife.
Design 2b: Large, Rectangular Wooden Planter Box
- 8x 12-foot lengths of 2x6s
- 1x 12-foot length of 2x4s
- 1x pond liner, 8×12 feet
- 1x landscape fabric, 8×12 feet
- 1x 1-inch poly pipe for overflow, plus adapter, screen clamp
- 1x 4-inch wide perforated weeping tile, 10-feet long
- ½-yard coarse gravel
- 1 ¾-yard soil
Cut eight 12-foot lengths of the 2x6s into 4-foot and 8-foot pieces to produce four individual, 4×8 feet completed beds that will be about 2-feet high. Then cut one 12-foot length of the 2x4s into the appropriate lengths to provide the bracing at each corner, and at the half-way mark of the long sides. After fully constructing the frame, level the area that it will sit on, remove any rocks from the ground, and put the frame in place. Then, line the inside with the pond liner.
Install an overflow drain in the top of the lowest of the 2x6s by drilling a hole directly through the side, a few inches above the bottom of the bed. Place a screen over the end of the tube, on the inside of the bed, to keep out unwanted pests. To allow the excess water to spill out, you need to make sure that the water can leave the bed, either with a designated spillway, or just raise the bed up on shims so the water can fall away and leave the periphery.
A 10-foot length of 4-inch, weeping tile is then laid diagonally along the bottom, and brought up one corner to serve as the fill-pipe. Coarse gravel is then added, up to the level of the top of the lowest 2×6. The gravel fills the lower section, and water percolates through the rock to fill the reservoir. Landscape fabric is placed on top of the gravel, reaching up the sides and ends of the bed to separate the soil from the reservoir. Once that is in place, the beds are then filled with soil.
As an option, planks can be added around the top edge of the bed to provide a comfortable seat when gardening. 6-inch wide deck boards are ideal for this purpose. Use two 10-foot lengths for each bed, miter them in the corners, and screw them into place.
Design 2c: Elevated Wooden Planter
This design is 36-inches high, 30-inches wide, and just under 6 feet long. Assemble a frame using 2x4s or 4x4s to make 4 legs at 36-inches high, with four shorter pieces cut to 23.5-inches high. You will also need four 10-inch pieces, in addition to two 30-inch cross beams, and use these to make a frame. For your cross braces, use two more 2x4s, about 6-feet long each.
Build the box, and line the bottom with some 6 mil plastic sheeting, or another plastic liner or barrier. Pull it over the top of the box, and secure it by screwing in a 2×2 board, and trim it out with a 2×4. Drill them together to hold the trim. Then, line a 3- or 4-inch piece of weeping tile on the bottom. Drill a drainage hole in the side of the box, and fit a PVC pipe through it. This hole could be oriented to overflow into another bed via gravity feeding. This way, as the bed overflows, it drains into the grow area of the other bed, filling that one up simultaneously, thus reducing water waste.
You can fill the rest of the reservoir with pea gravel to fill in the empty spaces around the weeping tile. Then, cover the reservoir with some landscape fabric, and fill the bed with potting mix, watering each layer of soil every 2-inches or so as you fill it up. When this is finished, cover the soil with some straw (not hay), and start planting.
Design 2d: Wood Pallet Wicking Bed
- Wooden pallets
- Political signs
- Scrap wood
- Old tarp or plastic liner
- PVC pipes
- Tumbled glass or gravel
For this design, you can use shipping pallets because they’re free and easy to find, but any salvaged lumber will do. Take one pallet, and measure half-way down its length, drawing a line perpendicular to the cross beams to create two equal halves. Then, measure each of those two halves in half again, and cut it to make four equal pieces. Then cut off the two end portions to create two equal, wall-like sections. Leave the remaining middle section uncut, and use it for another project, or cut it again to make two more pieces of the wall.
Take the pallet pieces and stack them upright, assembling them into a box. Start by setting them upside down on a flat surface, like a driveway or pavement, so that the top will be flush with itself. Once you’ve got them all aligned, screw them together with a drill to make a box, and flip it over. Then get some salvaged wood planks, and screw them over the rim, on the top of the pallet walls, to make a flat seat to sit and rest on when pruning or harvesting.
Choose the spot in your garden where you want the bed to be located, orientating it the way you want it. Then, put the finished box in place, and cut away the dirt around the perimeter with a shovel. Then, lift the box away and level out the ground beneath it, simultaneously removing any rocks. When finished, set it back into place and check to see if it’s level. Get some old political signs, flat corrugated plastic, old carpet, plywood, or any other material to use to line the inside of the bed. These will help fill the gaps in the pallets and protect the liner. If using political signs, measure them to be equal in length and height to the inner spaces of the box, and cut it with a razor. Then, line the sides and bottom of the frame with the signs.
Next, line the inside of the bed with a waterproof plastic tarp, or plastic pond liner, going all the way up the sides and covering the signs to create a waterproof layer. The tarp should be big enough to go out a little bit outside of the box. Then get some straight wood trim, set it on the side of the box over the tarp, and roll the tarp around the trim a few times. Then hold the trim on the side, level with the top of the box, set just above the reservoir, and nail it into the side of the pallet to secure it in place.
After putting the liner in the bottom, add 4- to 6-inches of crushed glass, pea gravel, stones, or broken bricks and pots in the bottom to create a reservoir. Then, fashion an overflow tube by cutting a length of PVC pipe long enough to go all the way across the inside of the bed, laid flat on top of the reservoir, and make a series of holes along it with a drill. This drainage pipe will lie on top of the reservoir, connected to the bulkhead fitting, and extend across the entire length of the bed to ensure even drainage. This will act as the overfill line and overflow spout, allowing the water to flow out of the bed when it reaches the top of the reservoir. Lay it on top of the crushed glass or filler on one side of the bed, right where the soil meets the reservoir. The holes in the PVC pipe should be facing down, towards the bottom and forward to the side, opposite the overflow hole, so that water will flow out easily.
Next, cut a thin length of 1-inch wide PVC tubing to about a foot or two long, and stick it in one side of the bed, standing vertically. This will be the feeder tube, through which water is deposited down through the grow bed. You could also use bamboo, or any other suitable material. Rest it right on top of the crushed glass or filler, or going down about 1-inch or so into the reservoir. If you have a long enough drain pipe, or some elbow connectors, then you can bend it up the side of the bed and use it as a water fill pipe.
Then, lay down a burlap sack, weed mat, or agricultural sheet over the filler in the reservoir to act as a barrier between it and the soil above. Wrap the fabric around the fill spout, or cut a hole in it to allow it to go through, and secure the fabric around the spout with a rope, twine, or rubber band. Lastly, tuck the fabric up into the corners, and fill the box with potting soil.
Design 2e: Corrugated Metal Planter Box
This bed uses cedar planks to create a wooden frame that holds in some corrugated metal siding, which makes up the walls of the above-ground bed. Use pressure treated plywood to prevent rotting on the inside of the whalers and increase its longevity. Also, clad the whole box with cedar fence boards, which resists rotting and repels pests. Since this bed will be lined with plastic, the wood will not come in contact with the growing medium, making it safe to use treated boards if they are available.
When you’re ready to assemble the walls, put them together using “whalers”, or 2x4s with the thick end perpendicular to the plywood, and bind them together using a lap joint. Space the whalers around the box to resist bending and bowing of the heavy soil.
When finished constructing the frames for the bed, move them into place to establish the best position for your garden beds. Mark out their perimeter with spray paint or flags to set a design for how you will orient them. Then, remove them and excavate the grass inside the perimeter to make a shallow ditch that contains the gravel, and put the beds back in the ditch to hold them firmly in place. Ensure the garden bed is level so that it fills up evenly. Use a purpose-built pond liner, available from landscape suppliers, and line it on the inside of the beds.
Next, start creating the reservoir by using some absorption tanks, which are similar to plastic milk crates. These have many empty voids in between a networked lattice of plastic struts, connected all throughout its interior. Gravity pushes the water down and into the absorption tanks to be rapidly dispersed in the reservoir. The absorption tank holds water within the voids, and as water is brought up by the plants’ roots, it rises through the soil and falls back down again to create a water circulation system within the planter. This keeps the water fresh and more available for the plants.
These absorption tanks sit flat on top of another plastic material, called the drainage cell, which is composed of multiple, hollow plastic cubes connected together in a series. This, in turn, lays flat on the bottom of the reservoir. The combination of the absorption tank and the drainage cell serves as a reservoir under your planting soil, and helps facilitate better drainage and water circulation. The drainage cells and the absorption tanks should be wrapped in what is called a geo-fabric. This fabric prevents sand and soil from getting into the cells or the absorption tanks, and also allows water to pass through easily, so it can rise and circulate throughout the system. Simply seal them up like you’re wrapping a gift box, and cover the edges with duct tape to seal them. Put a layer of sand on top of the absorption tank, and then place some soil and potting mix on top of that.
After installing the drainage cells and the absorption tanks, install a fill pipe using a simple PVC pipe. Then, install an overflow pipe into the side of the bed, located at the top of the reservoir. Drill a hole in the side of the planter box the same size as the pipe you will use as the drain spout. Then, insert a pipe through it to act as a water outlet, and seal the outside of the outlets with some silicone. Next, fill the planter with sand to approximately 5 to 10 cm above the level of the absorption tanks. Level this sand layer off, and then flood the garden bed with water until it overflows. After flooding the sand for the first time, it will subside and reduce in height a little bit. Add a little bit more sand, and level it out again, making sure that it’s about 5 cm above the absorption tanks. Then put some geo-fabric over the top of the sand, and bring in your planting soil.
Design 2f: IBC planter
If using IBC containers, you’ll need to remove them from their metal frame. Get a drill, a pair of pliers, a marker pen, and a big square measure, also known as a carpenter’s square. In addition, you’ll need an angle grinder, a jigsaw, or a hacksaw. Use these to cut the metal frames in half with a jig saw to free up the plastic containers. Once that’s done, file down the edges where you cut the metal, and flip them over to use as frames to hold the beds.
Once you have taken the containers out of the frames, cut them in half to make two equally sized beds, and paint them on the outside with a dark color to prevent mold growth. Also, be sure to plug up the drainage holes in the bottom by putting a bead of silicone around the edge of the tap. Then, screw on the cap to plug it up. This will ensure water does not leak out.
To assemble the overflow pipe, get a 19 mm, or ¾-inch wide, barbed pipe joiner or straight joiner, cut to 3- or 4-inches long, with an equally sized top hat grommet, and a shade cloth or other screen. Then, drill a 22 mm, or 7/8-inch, wide drainage hole into the side of the container (big enough to fit the grommet) at the top of the reservoir, and clean up the edge of the hole with a blade or file. This will create a suitable hole for the grommet.
Put the end of the barbed pipe joiner in the center of a square-shaped piece of shade cloth, and fold over the top and bottom to make an S-shape. Secure it with a zip-tie, wire, or twine, tying it up tightly. This should stop any sand from washing out. Insert the rubber grommet through the inside of the overflow hole, popping it in. Then wet the inside of the grommet a bit to lubricate it, and pop the end of the pipe with the joiner straight through the rubber grommet from the inside. Once through, the barb in the joiner should push neatly against the rubber grommet, making a water-tight seal.
For the reservoir, get a 5-meter long length of 4-inch weeping tile. Lay it on the bottom in a coil-shape, and fill in the empty spaces around the outside (between the walls and the weeping tile) with gravel or large rocks 3/4-inches in size or bigger. Be sure that you use enough gravel so that it is in contact with the soil or sand in the Intermediary Zone, and the soil does not touch the weeping tile. This is so that no soil or compost mixture will ever be sitting in water. Instead, the water will drain out before it reaches the soil. However, be sure to leave the bottom part of the barrel, in the middle, uncovered and bare to create a moisture-retaining pool area that will be filled with sand, acting as the wick.
Cover the rocks with a shade cloth, and then fill the middle of the reservoir with sand up to a point just above the overflow line. The water will fill the voids in between the rocks and wick up the sand into the dirt. Put a shade cloth over the top of the sand, and then loosely lay down a 3- to 4-inch thick layer of sugarcane mulch. This will assist the wicking action in the soil, and it will slowly break down over time, eventually becoming food for the worms. You could also use a shade cloth or weed mat instead of the mulch, but these are inedible to the worms, and will not decompose. Lastly, add the soil, filling it up as high as you can, but don’t go past the height of the watering tube.
Design 3a: Recessed, Tin-sided planter
You can build a wicking bed by making one from tin sides, with the bed having a height of 1 ½-feet, or about 45 cm. First, level off the bottom and put down a layer of woven weed mat to give the plastic reservoir some protection. Then, drill out a drainage hole through the side, using a 16 mm drill bit. Put a single barbed irrigation joiner through the plastic lining on the insides, with some shade cloth wrapped over the inside end and tied with a plastic zip-tie. Be sure to drill the drainage hole before adding the liner, because when you drill through metal you always create some sharp metal pieces. If you put the plastic liner in and then try to drill the hole, or if you put it in and don’t clean out all the small leftover shards, then you could tear through your liner, causing the unit to fail.
After drilling the hole, then put the plastic liner in, fitting it inside the bed. As the roots grow down, they will find the water and grow out and to the sides. After this happens, they could then grab hold of the liner and pull it down, compromising the reservoir. To prevent this, pull the liner up the sides, all the way to the top of the bed, and cut it off about half-way above the side of the metal wall. Make sure the plastic is fairly loose in all the corners, and is not held down too tightly, or else all the weight on it can rip the plastic.
For the reservoir and the fill-pipe, use a 4-inch wide slotted drainage pipe with sand or gravel on top. For this bed, which is long and narrow, the drainage pipe is laid on the bottom over the pond liner, extending all the way from one side to the other, with one section going up the wall and sticking out over the top. This side will be used as a watering pipe to fill up the bed. You could also coil the drain pipe around the bed, if you have a longer section, to create a larger void to hold the water. The sand goes over the top of the drainage pipes, up to a depth of 12 cm, or about 5-inches. The sand should completely cover the drainage pipes so that the soil is not constantly resting in standing water.
If you live in an area that gets heavy downpours, protect your bed from flooding by going up the side walls with sand by another 3-inches, or 7.5 cm, and then makes slots with a sharp knife or box cutter in the plastic, parallel with the bottom of the bed, every 1- or 2-meters. This will provide additional drainage holes for water to drain out through the side slits, in case the water ever gets above the overflow line and doesn’t drain out quickly enough. You could also simply use a larger pipe for the drainage spout.
After adding the sand, lay down a layer of shade cloth or sugarcane mulch in between the sand and soil, and then fill the bed with soil.
Design 3b: Recessed, Sub-Irrigated Planters using weeping tile
The finished planter is 30-inches wide, 75-inches long, and 16.5-inches deep. It is built with three rows of 2x6s, part of it being recessed into the ground. There are also two overflow drain tubes located on the back of the box. Everything below those tubes holds the water reservoir.
Start by fitting the pond liner in the box, ensuring the sides go up by about half-way up the walls. The lower-chamber that holds the liner needs to be one continuous, uncut rectangle on the bottom so that it won’t leak. Weigh down the edges and corners of the liner with some bricks or stones, and then fold it so that it fits snugly along the edges and overlaps itself in the corners to make a tight fit, like a Chinese take-out box. To achieve this, fold the flaps over in the corners, and cover them with a longer piece of the liner. This will make your lining completely waterproof. Next, staple up the sides along the edges to hold it in place, above the level of the maximum fill level in the reservoir. Then, run a sharp knife or box cutter all along the perimeter to cut a clean edge.
To make the reservoir, get some black corrugated drain pipes, and cut one of them to fit inside the box with the liner. Cap it with a screen, and lay it down flat inside, running horizontally across the floor, parallel with the short side of the bed. Lay the capped pipe flat in the bottom, aligning it with the overflow spout in the side of the bed so that the water in the reservoir can easily flow out when it reaches the fill line. Then lift it up, and puncture a hole in the screen at the point where it meets the drainage pipe. Next, set it down in place, sticking the overflow spout into the mouth of the weeping tile, pushing it through the hole in the screen. Then fill up the rest of the reservoir with longer sections of corrugated drain pipes, running them parallel with the long sides of the bed. Try to fill the reservoir with the weeping tile as much as possible to create more hollow void spaces.
Be sure to allow a little bit of space in between the pipes to let sand or potting mix get in between the spaces so that they can wick water upwards. Consider cutting the weeping tile into shorter sections to make several pieces of the weeping tile the same length as the width of the weeping tile, or about 4-inches. Take these short sections, turn them over 90 degrees so that their open ends stick straight up and down, and fill them with sand or soil to create a wick.
For the fill tube, use a PVC tube, anywhere from 1-inch to 3-inches wide, or big enough to construct a sort of fill-cone on one end using the top-half of a plastic bottle. Then, cut off the other end of the pipe at an angle to create a beveled or chiseled edge. The fill tube should be anywhere from 1- to 2-feet long, or longer, depending on your preference and the height of the bed. After preparing the fill tube, locate the spot for the fill pipe on one side of your bed, opposite the overflow tube. Then, drill a hole into one of the corrugated drain pipes at this location, just wide enough to fit the fill tube, and fit it straight into the hole. After inserting the fill tube, apply some tape around the seal where the PVC pipe meets the weeping tile, or wrap a shade cloth around it. This will keep more soil from falling through.
Prep your site by flattening and leveling it, removing all the rocks, but leave a base layer of soil or sand. Start by drilling holes for the drain hole similar to the ways described above. Put the joints of the walls together, without drilling or gluing them together, just to get a sense of how they will look when completed. Then place the corrugated drain tube section up against the side of the wall where it will be when finished, and choose a spot for the drainage hole just below the height of the weeping tile. This is where you will drill.
Start by measuring from the end of the board, going in by 4-inches. Then measure up from the bottom of the board by 3 ¼-inches, and drill a ½-inch hole. Don’t make the overflow tube too high in the walls of the bed, as it should be between about ½- to 1-inch below the top of the weeping tile. This will permit the bed to hold plenty of water in the reservoir, but not overflow with it.
Be sure to take into account how high or low the end of the tube will bend and warp inside the reservoir, and whether it will bend up or down, because this could change the maximum fill level of the reservoir. If your tube bends sharply, then you can cut off the ends to make it a little bit shorter. The section of the tube on the outside can be cut down to about ½-inch long, which will reduce the chance of accidentally damaging it, like kicking it when walking.
Cut down the length of the drainage tube on the inside to around 1-inch, or just long enough to extend into the inside and below the top of the corrugated drain pipes directly in front of it. Be sure the overflow tube goes inside one of the corrugated pipes, and that the end of the valve is covered with a screen. If the tube is sticking in the mix, and there is no screen to keep soil out, then it will plug up quickly.
Start pre-building the walls on a flat surface by laying the boards on their sides, and fit them together. Make sure they’re level, and square
the corners to make a nicely sized rectangular box. Screw, nail, or glue them together, and drop it into place where you want to grow. Ensure it’s still level and stable, so that it doesn’t rock or wobble around at all. Then, put on the additional two rows of boards so that the box is three boards high.
Add supports on the sides using two long planks on the short sides, and three on the long sides. These are imperative to have because they add structural support and prevent the boards from bowing as they dry out over time. Before adding the supports, measure from the corner the appropriate distance, or to about 6-inches. Use a square measure to make it flush with the top and side edges. Clamp it into place, screw everything in to assemble it together, and move on to the next one. Use screws rated for use in treated lumber, and don’t forget to drill holes in the floor for drainage.
Alternatively, you can build some elevated beds by taking a piece of 5/8-inch thick treated plywood and building a stand for it out of 4x4s. The stand has to be pretty strong, as it will be holding a lot of weight. Build a full frame around the outside, with two cross pieces evenly spaced from end to end, and then set it on six legs. Cut sides and ends out of another piece of plywood, 16-inches tall, and then attach them to the floor by running a 2×2 around the edge. Be sure it’s set back far enough so that the outside of the sides and ends are even with the edge of the floor. Then run another wall across, 4-feet from each end, and stiffened with 2x4s.
Design 3c: Recessed Wicking Bed using a single, 50 mm AGI pipe
Step One: Dig a hole to a depth of 150 mm, ensuring it is level. This will form the water reservoir.
Step Two: Build up the sides by 450 mm with a solid material so the bed has a total depth of 600 mm (including the hole you just dug). Line the entire bed with good quality builder’s plastic or pond liner.
Step Three: Install a length of 50 mm pipe, a 90-degree PVC corner and a length of 50 mm slotted AGI pipe that will run the length of the bed, along the center. Place a cap on the end of the AGI pipe.
Step Four: Cover the pipe with scoria, pebbles, gravel or another media to a depth of 150 mm. Cover the scoria with a layer of shade cloth.
Step Five: Add 150 mm of water retentive sand, woodchips, or other material to the bed. This serves as the Intermediary layer at the top of the reservoir. Add a water tank tap outlet to act as an overflow at 300 mm by drilling and attaching it to the end of the bed. This sets the maximum fill line of the bed, but you could reduce the height of this fill line, if needed.
Step Six: Fill the remainder of the bed (another 300 mm or so) with a good quality soil and compost blend. Mulch well with a straw based mulch (to about 5 to 7 cm), taking care not to cover the PVC pipe opening.
Design 3d: Recessed, Self-Watering Brick Planter
A self-watering unit can be built using a brick planter. First, dig out the area for the planter and remove any dirt or rocks from the inside. Then, drill holes through the walls of the cinder blocks that you will use as raisers to allow water to flow in and out of the voids in the middle and through the sides.
Next, line the bottom of the planter with a sturdy pond liner and trim it just above the reservoir level. You should use anywhere between six to eight cinderblocks, depending on the size of your planter. Space the blocks out about 6- to 10-inches away from each other, ensuring they are evenly spaced to offer proper support for the soil. Lay the cinderblocks down on their sides with their openings orientated upwards. Inside these holes will be placed sand or soil to wick up the water from the bottom.
To make the drain for the reservoir, first drill a hole through the brick wall on one side, about 5- or 6-inches up from the bottom. Do this before you add the liner to avoid tearing it accidentally. Then, get a screw-on plastic drain (the kind you’d use in a sink), along with a hose washer screen to put inside it. Push the hose washer screen through one side of the plastic drain, and attach one end in the pond liner, going through the drainage hole and leading to the outside. Then, make a platform to hold the soil on top of the cinderblocks using wire mesh or another solid, porous material.
Once the drain and watering tubes are installed, fill one hole in each cinderblock with sand or soil to act as a wick for the water, and lay a layer of weed mat over the wire mesh on top of the cinderblocks. Then, cover the weed mat with a few inches of sand and flatten it out. Lastly, add a layer of mulch, fill the planter with potting mix, and put in the plants.