By Jim Demosthenes, TPL garden volunteer and Master Gardener
First made popular in Africa due to dry growing conditions, keyhole gardens are growing in popularity in other hot, dry geographic areas. From a view above, the garden is shaped like a keyhole because of a notch that is cut out of the round shaped bed to enable access to a compost bin situated in the center. The compost bin is supplied with organic matter such as leaves, banana peels, and other kitchen and garden waste. The compost decays naturally over time. When it rains the decomposed compost material (fertilizer) seeps into the surrounding area within the garden providing moisture and nutrients necessary to grow plants and vegetables.
As part of the TPL demonstration garden, a keyhole bed was built in the summer of 2015. It was created over a base of woody debris, which 
is shown to enhance water retention and help build high quality soil (see diagrams). Last October, half the bed was planted with seed garlic grown organically in Midcoast Maine; this will be harvested around July of 2016. This spring, a different organic crop will be planted and cared for on the other side of the bed.
The expectation, based on the garden construction, is the lack of need to add any additional water to the garden, even during the warmest summer months. All of the harvest will be donated to the Midcoast Hunger Prevention Program (MCHPP). Future plantings of other vegetable and herb crops will continue to supply food to those in need.