Permaculture (short for permanent agriculture) uses natural techniques to help the fertility and create more ideal growing conditions for plants. It is ‘permanent’ in the sense that one intercrops trees, bushes and vines with annual vegetables, so the gardens are always producing something. Their roots hold the soil on our terraced, hillside vegetable beds, the leaves of the trees make shade and add mulch to the soil (humus), and the ditches (swales) hold water long enough for it to seep slowly into the soil, where it is available to the roots.