The Keyhole Vegetable bed is a raised bed, 3′ 6″ high, the outer bed slopes down from a central hollow column. The access path (to center) is a compost bin: you fill it with kitchen waste, stable manure, grass clippings, etc., water will drain through and take all the nutrients with it. It feeds from below the topsoil, everything comes up from underneath. In Africa, this garden can feed a family of 6 through the 3 mo. dry period, when fields dry out. Perfect for small spaces!