A mulch is a layer of material applied to the surface of an area of soil. Its purpose is any or all of the following:- to conserve moisture to improve the fertility and health of the soil to reduce weed growth to enhance the visual appeal of the area A mulch is usually but not exclusively organic in nature. It may be permanent (e.g. bark chips) or temporary (e.g. plastic sheeting). It may be applied to bare soil, or around existing plants.