Raised Garden Beds are cheap, easy, and sustainable. They can be done in almost any yard, of any size, and make a productive replacement for expensive, non-productive grass lawns. They are beautiful, reduce noise, and provide shelter from the wind and sun. In addition, they also keep weeds from growing in your soil, prevent compaction, provide improved drainage, reduce erosion, and help repel pests.
- 4x 16 in. long 4x4s
- 2x 8 ft. long 2x12s
- 2x 4 ft. long 1x12s
- 6x 12 in. long pieces of ½ in. PVC pipes
- 6x 10 ft. long pieces of 3/8 gauge rebar
- 24x 3 ½ in. #14s and 12 ½ in. #8s
- 3x 3×5 ft. rolls of ¼ in. mesh hardware cloth
- 12x 1 in. galvanized tube straps
- Planting soil and compost (Approximately 16 cubic ft. each)
- Drill and drill bit (5/32 in.)
- Pencil and ruler
- Square rule and level
- Staple gun
- Wire cutters
- Optional, 4x adjustable woodworker bar clamps, 2x short (12 in.) and 2x long (6 ft.)
Here are some tips on planning, building, protecting, and irrigating raised bed gardens.
- Select a location with plenty of sun and easy access to the sides.
- When determining bed placement, consider what species you will plant, how much sun, water, and shelter they will need. Also consider the direction of the prevailing winds, the presence of any channels of water running through the site, what animals may need to cross it, and the need for walking pathways.
- Try not to interfere with these channels or paths, or you may have to redirect them.
- To prepare the site, get rid of turf and weeds.
- Outline the bed dimensions on the ground with chalk or string.
- Beds should be wide enough to support sprawling tomatoes, but narrow enough to reach easily from both sides.
- A box of about 6 ft. long by 3 ft. wide and 1-2 ft. tall will give a sufficient grow area. Other dimensions could be 6×4 ft. or 3×5 ft..
- Orient the beds along the North-South axis to capture more available sunlight. More exposure to the sun warms the beds, allowing greater plant diversity and extending the growing season.
- Align the beds in straight rows or columns to simplify the installation of an irrigation system.
- Dig with vertical strokes along the outline, just deep enough to bury about half of your first course of lumber. Dig up the top layer of sod and check the ground with a level to make sure the base is even.
- Cut some weed-suppressing landscape fabric down to the size of the boxes. Leave an extra 6 in. along each edge so the fabric extends past the outer edge of the wooden frame, and lay it down over the bare soil.
- Build each wall separately using a durable building material. Almost anything could work, including wood, rock, brick, concrete, or interlocking blocks.
- If using wood, use rot and insect resistant woods like Port Ortfood cedar or Redwood. Try untreated hardwood or recycled railway sleepers. Do not use any chemically treated woods.
- Prevent the “bathtub effect” by digging down a few inches deeper, and put a layer of coarse stone or pea gravel in the excavation. Drainage is built into the bed walls which hold the soil in place to prevent erosion.
- To keep out burrowing pests, lay down a bottom layer of hardware cloth or a metal screen.
- Fasten all the walls together and put the bed into position.
- Position the boxes on the fabric and level it. Cut away any excess fabric.
- Keep everything stable by installing a railing that runs around the top of the bed. This will give you a flat surface to sit or lean on when gathering.
- Fill the beds with a soil-and-compost blend to improve soil fertility.
- To suppress grass and weeds, soak lots of newspaper and cardboard in water and lay it on the bottom of the bed. Then plant your seeds.
- Space the plants closely together to make yields go up and crowd out weeds.
- Use galvanized pipe straps to mount a 1 in. PVC pipe inside the bed walls. Cut a ½ in. flexible PVC tubing twice as long as the bed’s width. Bend it and mount it above the beds to create a framework for a cover.
- A simple framework of hoops and a cover can extend your growing season in cool areas, conserve moisture in dry areas, prevent your plants from getting burned on warmer days, and protect plants from birds or insects. Use a lightweight plastic tarp or sheet fabric, held in place with a clip, to create a cover to protect against the sun.
- A basic irrigation setup consists of a series of valves, with a faucet or hose-bib attachment, that prevent back flow into the plumbing.
- From these, attach supply lines of flexible ½ in. poly tubing. Lay the tubing along the beds in lines 12 in. apart, winding it between the plants, and cover it with soil. Fit the sections together with compression elbow and T-fittings.
- Install drip emitters at 12 in intervals. Close the ends of each line with hose-end plugs and caps.
- Attach the tube to an optional timer or regulator-reservoir to deliver the water evenly and gently.
- Set your system to water early in the morning or in the evening so that water-use efficiency is maximized, as less water will evaporate. The plants will also be healthier, and better resist diseases.
- Fill the spaces between the planters with woodchips and border them with cinder blocks. You can fill the spaces inside the cinderblocks with soil, and plant within them, too.
- Usually, the bottom of the planter should be left open to the ground, permitting plant roots to grow downward.
- You can also lay a brick path between the beds to create a convenient walkway.
- If using an irrigation system, you can lay down the hoses in between the beds in the pathways, and cover them with woodchips to prevent compaction.
If you want to have an herb-producing garden, but have limited space or sun, and want to save time managing your garden, then creating an Herb Spiral might be a good option. The Herb Spiral combines a two-dimensional pattern (a spiral) with a three-dimensional one (a mound) to form a beautiful, space-saving living sculpture that has several microclimates. This creates a multifunctional, elevated growing mound, or a modified version of the raised bed, that is highly productive and energy efficient, and can supply herbs and spices in one space with low maintenance.
They can be built on a base as small as a 1 m wide, fitting a large amount of growing area in a compact structure, so even the smallest garden can increase your vertical growing potential, providing an area large enough to accommodate all your common culinary herbs. Another multi-functional shape to use when building an herb spiral is an oval, which allows you to take advantage of a sunnier position, and plant it with vegetables instead of herbs.
There are at least twelve advantages to using Herb Spirals, with its mounded spiral-ramp, which are discussed in more detail below. The advantages of Herb Spirals are they:
- increase the growing area
- create multiple microclimates
- can be built with numerous materials
- extend the growing season
- improve drainage
- improve plant health
- provide wind and sun protection
- increase aesthetic appeal
- save money, time, maintenance, and provide easy accessibility
- retain nutrients in the plants
- allow easy companion planting
- permit easy irrigation
All this makes the Herb Spiral a practical and attractive solution for urban gardeners.
Firstly, Herb Spirals increase the growing area, maximizing the surface area for planting so you can grow more food in less space. The creator of the Herb Spiral and co-founder of Permaculture, Bill Mollison, describes his reason for the design in his book Permaculture: A Practical Guide for a Sustainable Future (1990). In it, he says that the spiral shape is useful in because it allows us “both to create compact forms of otherwise spread-out placements and to guide water and wind flows to serve our purposes in landscape.” The spiral is inspired by patterns found in nature, being so ubiquitous because it is the most efficient to store energy and save space.
Secondly, the spiral design contains various different microclimates, creating more habitats and increasing biodiversity. This allows urban gardeners to grow a diverse range of herbs that prefer different growing conditions all in the one garden space. In a typical garden bed, all the plants are grown at one level, making all the growing conditions the same. However, this design offers you multiple options in a compact space, with a drier zone at the top and a moist area at the bottom. These microclimates are created because shape of the mound creates differentially shaded zones, with some sides getting more sun or shade than others. The side facing the sun will be warmer, acting as a thermal mass, absorbing warmth, and becoming drier. This favors hardy, heat and sun worshipping, oil-rich herbs. The side opposite the sun is shadier, and more moist, which favors water- cold- and shade-loving plants.
Thirdly, Herb Spirals can be built in a number of different ways, using various materials, including stones, bricks, cinderblocks, wood boxes, logs, metal containers, clay pots, chicken wire with rocks inside, glass or plastic bottles, etc. The stones, rocks, bricks or blocks used to build the spiral form the backbone of the spiral structure, holding in the soil, plants, and organic materials. The niches in between the bricks or rocks can also be planted with shallow rooted ground cover herbs like oregano or pennyroyal. Use whatever materials you have easy access to or can use to retain the soil. Look in landscape and salvage yards, which may have small quantities of blocks or building materials on sale for a bargain, like end of line sales, cracked or chipped pavers or bricks (which can be faced inwards on your spiral), and rocks from cancelled jobs, or ones advertised in the classifieds or weekend garage sales.
Fourth, the mound will retain heat absorbed during the day and insulate the garden at night, keeping it warm when temperatures drop. This will extend the growing season by keeping the plants warmer and reducing damage from frost. Some materials are better at retaining heat than others. Hard, dense, heavy materials like stone, brick, concrete, etc. will act as a heat sink and retain more heat than wood, glass, or metal.
Fifth, this design maximizes drainage that further helps to create different microclimates that will favor areas with high rainfall. Dry climates will also benefit from the moisture retained at the base of the spiral so that no water is wasted. Drainage is improved in this design because it utilizes the force of gravity to drain water freely through all the layers. When watering, the spiral is wetted from the top, and because water always drains downward, the moisture filters down to the bottom, creating different moisture zones. And, since the top of the mound is exposed to the most sunlight, the highest levels on the spiral tend to be drier, favoring herbs that prefer dry conditions. This makes the base wetter, as the water will tend to accumulate on the bottom, favoring herbs that enjoy more moisture. An added benefit of this design is that it makes it possible to grow plants that dislike excessive soil moisture in areas that can become waterlogged, while growing other plants that enjoy more moisture alongside them.
Herb Spirals can also be built so that water flows down a ramp that leads to a drain at the bottom. The bottom of the spiral can be closed off with bricks, rocks, or blocks. Or, it can be left open to allow water to flow into a small pond or bog garden at the bottom, towards the northern end, which helps reduce evaporation and maximize moisture and shade. This is ideal for edible water plants that prefer a wet environment. Beneficial creatures like lizards and frogs will move in to your pond or bog garden at the bottom and help with pest management by eating the insects.
Sixth, your herbs will be healthier when you meet their specific growing needs, making them thrive and be more productive. Group the plants together according to their growing preferences and conditions, and your own tending habits.
Seventh, the mound creates its own shade on the side opposite the sun, providing protection for vulnerable plants. It also blocks the path of the air, and can help create a screen that shields plants from harsh winds. When planting, position your plants like an umbrella, with taller herbs shading smaller ones that need more protection from the sun.
Eighth, it is a beautiful, aesthetically pleasing garden feature, particularly when most gardens over utilize horizontal beds and containers. This creates a striking, curved spiral that draws the eye, making a focal point for your garden. You can also use Herb Spirals to hide ugly yards, or to cover concrete surfaces.
Ninth, save money, time, and maintenance. Considering the rising cost of food, a herb spiral will quickly pay for itself after you’ve been harvesting for a season or two. They are easy to use and access for maintenance, as they can be placed virtually anywhere. They are also built at waist height, allowing you to reach all points of the spiral effortlessly, without bending, from any side. After their initial construction, only minimal maintenance is required, such as watering, harvesting and topping it up with mulch.
Furthermore, growing the bulk of your food nearby is extremely energy and time efficient. No extra time or fuel is wasted traveling to the grocery store, because you don’t have to go there for food as often. You won’t need to refrigerate the food for nearly as long because it stays fresh growing in the ground. This reduces waste by itself, because much of the fresh food we buy ends up in the garbage, or ends up rotting in the fridge, uneaten. By growing your food nearby, you can pick what you need when you need it, reducing wasted food and money.
Tenth, freshly picked vegetables retain more nutrients than those that are picked and preserved for a long time. This means that your plants will have their maximum nutritional value when they get to your plate.
Eleventh, the design allows for easy companion planting and integrated pest management. Many herbs have mutually beneficial relationships with other plants that can be used to assist other plants in growing or fertilization. Flowering herbs attract beneficial pollinating insects like bees, butterflies and wasps. Growing the herbs closely together helps the overall health of your garden, improves flavors, and aids pollination. Include herbs like chamomile, borage, calendula, French marigolds, nasturtiums, and the Orange Cosmos flower to serve as excellent companion plants.
Twelfth, watering them is simple and effortless, and can be done automatically with a pipe going up the center up the center of the mound, or with a drip irrigation hose laying on top of the spiral ramp. Alternatively, you can use a central sprinkler to water one or several mounds at once.
Building the Herb Spiral
Choose a spot in your garden about 2×2 m across that’s close to your kitchen. Clear the area of grass or weeds and level it with a shovel. Dig a small hole at the lowest point on the mound, down at the end of the spiral. This will collect water as it flows downslope and serve as a frog pond. Make sure the pond is placed in a shady spot, preferably at the northern-most point to reduce evaporation. Then, put a shallow plastic garbage can or container into the hole to act as a reservoir. Cover the pond temporarily to keep dirt or rocks from falling inside while you are working.
Once you have chosen the right area, flattened it out, and dug your pond, then lay down some sheets of cardboard over where you want to place the spiral. This will prevent unwanted grass or weeds from growing, provide mulch for the worms, and also provide a flat surface to help draw the spiral. Mark out the area where you want to locate the spiral with turf marking paint, some small rocks, or flags. The spiral should be about 1.2-1.8 m in diameter, or 4-6 ft. The typical width of an herb spiral is typically 1.5-2 m (5-6.5 ft.) wide in diameter at the base, ascending to 1.0-1.3 m (3.2-4.2 ft.), with the center of the spiral at the highest point. The space you use for the spiral should be approximately 1.6 m, or just over 5 ft., in diameter. Using this size, a simple, flat circular bed has an area of 2 sq. m. However, if we create a 0.5 m high mound, the surface area increases to 2.4 m, adding an extra 20% of available planting space. The higher the spiral (within reason), the more area we gain.
If using bricks to make the walls, start by building up the spiral from the center, working your way outwards and upwards. Use straw to fill in the empty spaces under and around the bricks if they won’t fit right. Make sure you use straw instead of hay. Both are similar, but straw doesn’t contain any seeds. If you are using stones, choose ones that are nice and flat. Separate the stones in piles based on width or thickness and start with the flattest, thinnest pieces. Start laying stones to build up the spiral, laying the biggest ones at the bottom, and work your way inwards from the lowest point near the pond, stepping up in the thickness of the stones as you work upwards and inwards. Build the spiral up in layers, using thicker, wider stones on the bottom of the spiral as a foundation, and position the stones to keep each layer relatively flat so the following layer is more stable. If you need to, lean the stones inward to make the wall more stable, or use small stones to wedge larger stones to stop them from wobbling.
Once you have completed the first layer of stones to form the base, then gently fill the bottom of the spiral with straw and top soil. Add a shovelful of compost for every square meter of soil to add extra nutrients to the soil. Continue building upwards towards the center, and add dirt in the areas between the stones or bricks as you go higher up, and then add stones or gravel on top of it. After reaching the top, fill in any empty spaces with more straw as compost. Cover the straw and gravel with a mixture of native soil and fertilizer or potting mix. If you want, you can fill the spiral completely with straw on the bottom, building up and watering as you go, and cover it with soil or potting mix on the top. When finished, leave the soil alone to settle for a week before planting.
When finished, make sure the center is several layers high, and water the soil liberally. The center of the spiral can get up to 4 ft. high, depending on the diameter and slope of the mound. Lastly, fill the garbage can in the pond with small stones on the bottom, using larger ones to line up the sides, and fill it with water. Add more stones around the top edge of the pond to hide the can. Try putting stepping stones around the edge so you can access the spiral without getting your feet muddy.
Before planting, lay out your plants the way you want to plant them. Try to combine plants with different colors and habitats closely together. Position the plants in the spiral based on whether they prefer dry or wet soil, as well as shade or sun. Also consider the expected height and spread of each plant to take advantage of natural shading. Put sun-loving Mediterranean herbs (like Basil, Sage, Lavender, Marjoram, Thyme, Chamomile, Coriander, Rosemary, etc.) at the very top, on the south-west, south-east, and southern sides, where it’s windier, sunnier, and drier. These sections are more windy and sunny, and plants here will become susceptible to drying out. The north-east and north-west sides of the spiral, where it wraps around toward the center, will only be exposed to the gentle morning and afternoon sun, making it damp and slightly-shady. This is ideal for more delicate plants adapted to cool or temperate environments, like Chervil, Mints, Watercress, Chives, Parsley, Sorrel, Tarragon, etc. The Northern-most side of the spiral is best for shade and wet-loving plants, like Dill and Cilantro, and makes a great spot to place a small frog pond.