With spring just around the corner, how about starting construction on a “Keyhole Garden”? First made popular in Africa because of the hot, dry climate and lack of fertile soil, the round garden bed looks like a keyhole from above. Because of the notch from the outer diameter to the center of the bed, it is easy to access to the central compost basket and tend the garden. The “key” to this raised garden is an active central compost pile that leaches out nutrient-rich “compost tea” when the plants are irrigated by pouring water into the compost basket. Positioning the notch facing north allows the planting bed to take full advantage of the sun. Be creative when building your garden by using materials you can salvage or already have on hand. The outer walls may be 3′ to 4′ high and built from bricks, stones, broken cement pieces, sand bags, or fencing and boards driven into the ground. The best size is 6′ to 6.5′ in diameter. If larger, plants at the outer edge may suffer from lack of water and inner plants will be harder to reach. The bottom layer of the
bed needs to be filled with drainage material such as rocks, broken tiles and flower pots, brick pieces, twigs, branches, rusty cans, and even old animal bones. Use cardboard, newspaper, manure, leaves, straw, lawn cuttings, old potting soil mix, and wood ashes for your next layer. Use top soil for the planting surface. Make sure the bed slopes gradually from the center and away from the compost basket in the middle for adequate dispersal of the compost tea. The compost basket should be a 1′ to 1.5′ diameter tube tall enough to extend from ground level to well above the center of the bed and made of material that will allow water to seep through it, such as chicken wire, fencing, or sticks. It needs to be strongly reinforced with rebar, sticks or anything that will hold it in place and keep it from collapsing. Kitchen waste and garden clippings, worms, and household gray water are then added to the basket to encourage decomposition. During heavy rains, it’s a good idea to cover the basket to avoid having compost nutrients leach out too rapidly. Use your time now to construct your unique African keyhole garden and you can look forward to a bountiful harvest this summer.