Organic mulches include straw, leaves, manure, pine needles, leaf clippings, shredded bark, wood chips, sawdust, compost, composted sewage sludge, etc. Inorganic mulches provide a long-term ground cover. A weed-control mat should be placed below the mulch. Use a mat that allows water to penetrate. Marble chips, river gravel and crushed brick are popular inorganic mulches.
Weed control is important for water conservation.
Weeds will compete with desired plants for water and nutrients. A 2-inch layer of mulch is the best defense against weeds. Other methods of weed control in the home landscape include hand pulling, mechanical cultivation and the selective use of herbicides. Many plants require more nutrients than can be obtained from the native soil. Nutrients are added in the form of fertilizers.