Mulches provide a barrier that helps prevent moisture loss from the soil by evaporation. They also can be useful in maintaining cooler soil temperatures, controlling weeds, reducing soil compaction, and keeping produce cleaner. Plastic mulches Black polyethylene mulch is preferred because clear plastic mulch promotes weed growth underneath it. Plastics usually are available in rolls from 3-4 feet wide. They are placed over the row or bed, the edges covered with soil, and various sized holes cut for the different crops.
Black surfaces absorb heat, warming the soil for earlier production.
Later, the foliage shades the plastic, reducing the heating of the soil. These mulches work best with warm-season crops such as tomatoes, melons, peppers, and eggplant, which are usually established by transplant. Organic mulches Common organic materials used in gardens include compost, old hay, straw, leaves, shredded newspapers, peat moss, and grass clippings. Organic mulches serve as insulation, reducing soil warming in the spring, so later season use is recommended. They can be left in place and tilled into the soil during the fall as a source of organic matter.