Q. I have heard of a new type of raised bed system called keyhole gardening? What is it?
A. An African keyhole is a raised bed system and has been used in Africa for a long time. The idea is to enrich the soil as one grows plants, provide an efficient way to water and conserve moisture, protect the garden from critters, and allow for easy access. Recently, this style of garden has been used in America and modified slightly in sustainable garden use.
An African keyhole garden is circular in shape, with a small notch or keyhole built in for easy access. One- to 3-foot walls enclose the garden. The keyhole is an open circle or rectangle in the center of the garden. This is where food scraps, clippings, and water are added. The soil is mounded up to the central keyhole, and plants and flowers are planted on the slopes. A 6-foot- to 8-foot-diameter circle is more common.
Making a keyhole garden is a nice project to take on with neighbors and friends. Level the area where you want the garden. Locate the garden in full sun, away from walnut trees, close to a water source and reasonably close to the house. Use rock, bricks, cinderblocks or pavers to build the walls. Make the circle, and the notch. The notch just needs to be wide enough to walk in – about 2 feet in width. For those of you old enough to remember, the garden should look at completion like a Pac Man (or woman) with a small rectangular mouth.
No mortar is necessary, but its a good idea to place the wall material slightly inward and overlap the material when building as to prevent collapse of the walls.
In the center of the garden, place a 2- to 3-foot diameter cage made of chicken wire, stones or hardware cloth. The top of the cage should be at least 2 to 3 feet taller than the wall height but not so tall that you cant easily dump materials in the cage. When the walls and central cage are completed, line the entire garden and walls with cardboard, newspaper and then clean straw.
After lining, fill the garden, using lasagna-style layers, with soil, compost, leaves or straw, and composted manure. Make sure to incline the soil from the outside up to the central keyhole cage. Place some straw, paper, soil, kitchen scraps in the central key. Then plant the garden. Africans use herbs, vegetables, and flowers all together.
The garden is watered by flooding the central keyhole. Keep adding materials to the center keyhole as the year progresses. Mix the material occasionally. The garden is a breeze to weed and water and worth a try if you are looking for a creative sustainable way to grow vegetables, herbs or flowers.