Keyhole Gardening

Keyhole gardening is a method developed for areas experiencing severe drought and limited resources, specifically Africa. However, the concept is just as useful in other parts of the world and in your backyard. Keyhole gardens conserve water, and they provide plants with easy access to nutrients.

Keyhole gardens are a variation on raised bed gardening. Keyhole gardens are round raised beds that feature a notch in one side that provides access to a composting tower, or basket, in the middle. As compostable materials and water are added to the center of a keyhole garden, the water and nutrients spread out within the keyhole garden to feed and irrigate your plants. The loose, nutrient-rich soil makes it easy to grow edibles in even the worst conditions.

African keyhole garden (Send a Cow)

How to build a keyhole garden

Keyhole gardens are easily made with curb-scored old bricks, stones, or cinderblocks.  You can also use landscape cloth, wood planks or branches, wine bottles, old fencing panels, corrugated metal sheets - really, you can use anything that isn’t toxic. Use your imagination! Follow these steps to create your very own keyhole garden:

1. Mark off a 5- to 8-foot diameter circle on some flat, cleared ground. You can do this by tying a string to a stick or tool stuck in the ground in the middle, measuring out the proper distance, and then using the end of the strong as your guide to score the circle in the ground.
2. In the center of that circle, mark off a 12- to 24-inch circle, using the same method.
3. Dig a slight trench along the line of the larger circle, the width of your wall material.
4. Mark a triangle in the soil from the larger circle to the inner circle. This is your keyhole.
5. Build a central basket with a section of hardware cloth, chicken wire, or woven sticks.
6. Place a thick layer of straw or shredded paper in the bottom of the basket, and then fill with alternating layers of compost and straw or paper, watering as you go.
7. Create a short wall in the outer circle using bricks, stones, or whatever material you have available. [If you use a wall material that is compostable, you may want to line it with heavy duty (4 ml or more) plastic to prevent it from being broken down.]
8. Cover the bottom of your keyhole garden area with a layer of sticks and stalks, no bigger around than a broom handle, and no longer than a foot, about 5 inches deep at the basket and tapering down as you move outward. [This is a great way to put all those sunflower stalks and corn stover to good use!]
9. Cover the stalks with an inch and a half of wet straw. This completes your drainage layer.
10. Fill the outer circle with layers of topsoil, compost, and straw or shredded paper, banking the material up against the basket, and then water deeply.
11. Build up the wall and continue filling and watering until you have reached a height that is comfortable for you. 
12. If you live in an area with a lot of rain or strong sunlight, you may want to add a protective roof over the basket.
13. Plant crops in concentric circles, within your keyhole garden.
14. Add compostable materials to the basket as they become available and then water.

Sources of compostable materials

Most people know that yard and kitchen waste are compostable, but there are many other sources of perfectly acceptable materials for the basket of your keyhole garden or any compost pile. Remember that compostables are designated as “browns” or “greens” and that you should aim for a 50:50 mix of the two. Some interesting source of “green” compostables include coffee grounds and tea bags, often available for free from coffee shops, and fresh manure from local barns. [Manure from veterinary clinics is not recommended.]

​We throw away a profound amount of compostable “brown” material. Some sources you may not have considered include any paper or wood products (simply avoid the colored, slick, or waxed varieties), dryer lint, vacuum cleaner waste, shredded, unwaxed cardboard,  and even clothing made from 100% natural fibers. Rather than adding these materials to local landfills, you can transform them into plant or worm food in your compost pile, worm farm, or in the central basket of your keyhole garden.

Building a keyhole garden can help you get around the problems associated with heavy clay, compacted soil, and difficulties bending over. Check out this video about a heart-warming solution to starvation around the globe and  a fun new way to grow edibles in your own backyard!​