The built-in composter on this elevated bed lets you recycle your kitchen scraps and yard waste into nutrient-rich compost. Simply add the materials to the center compost basket, and as they decompose they add a steady supply of rich organic matter to the soil. The compost also adds moisture, helping to improve the garden's drought-tolerance. Pioneered in Africa, self-sustaining keyhole gardens produce an abundant harvest in a small space, with less work. Keyhole gardens are traditionally filled half-way with alternating layers of "brown" and "green” materials, similar to building a compost pile.