An important characteristic of mulch is its ability to insulate a plant and its roots from the effects of extreme temperature fluctuations. Ideal mulches must allow water and air to enter and exit the soil. They should be attractive, odor-free and stay in place. Also, ideal mulches should not compact or become a fire hazard. Although no single mulch material will meet all these requirements, select one that best suits the needs of your site.
Most gardeners use organic mulches.
These are derived from plant material and imitate naturally occurring forest or prairie litter. Gardeners can develop their own organic mulches by recycling yard waste such as chopped or shredded leaves, branches, wood chips, or grass clippings or they can purchase mulches from garden centers. An important value of organic mulches is that they continuously add organic matter to the soil surface. Earthworms and other organisms will incorporate this material into the upper soil area. When the planting bed is renovated, the gardener can work this organic mulch into the soil deeply enough to actually incorporate it into the root zone.