Keyhole Gardens: More Than a Shape

by Kymisha Montgomery, CGC Urban Agriculture Coordinator

I once thought a keyhole garden was simply the design shape of a garden or garden bed. Actually, I thought that for a very long time—until I was introduced to gardeners from Africa who showed me that there was so much more to it than that. Instead of thinking of the “tradition” keyhole garden bed, where an area is cut out for convenience and access, I now think of it as a place where nutrients are to be created and stored for your soil, like those created in Sub-Saharan Africa.

Essentially, a keyhole garden is a round raised bed garden with a bioreactor built into the center. It’s a type of permaculture because it is sustainable and regenerative. It can be made of anything that can contain the soil and is ideally 6 feet in diameter and 2 feet tall. In the center, compost is generated to continuously replenish the soil and crops as they grow, ultimately creating a healthy, nutrient-rich soil that your plants will appreciate. Because as we know, soil health is key to a thriving garden!

The 6-foot diameter of the original design is so that you’re able to reach the inside from all sides with minimal disturbance to the soil or the plants. Materials such as bricks and clay were used in the traditional African keyhole beds because they were sturdy enough to support the soil. The central composting area is also traditionally made with natural materials, like weaving tree branches and twigs together to form the composting basket. Most bioreactors today are made using hardware mesh or chicken wire, which allows the air to flow through the compost to help break down your materials. The mesh also allows for water to penetrate and flow easily from this station into the garden.  

What a brilliant and simple design!