Proper mulching in summer months keeps the soil cooler. Soil covered by black or clear plastic or dark organic mulch in early spring warms faster than bare soil. This allows earlier planting of warm-season crops. See figure 3.

Use light-colored paper such as newspaper in summer to keep the soil cooler. Organic mulches such as compost and sawdust also keep soil below the mulch layer cooler in summer. Dark soil warms much faster than light-colored soil. See figure 4.

Organic mulches enrich the soil as they decay and provide a better environment for plant growth. Soils high in organic matter are easier to till and better suited to vegetable gardening. Adding organic material makes soils more crumbly, especially clay soils that pack and crust.

Mulches help plants by gradually increasing soil fertility. An organic mulch such as straw or newspaper can be turned under the soil at the end of the season. This helps build the soil's organic matter content. Turn the mulch under as soon as the gardening season is over so it breaks down before the garden is replanted.

Most mulches also provide excellent weed control. Mulches do not prevent weed seeds from sprouting. However, weed seedling emergence is blocked by a mulch layer thick enough to exclude light. A 3-inch layer of mulch on the soil surface keeps most annual weed seedlings from coming through. See figure 5. Weeds that bread through are removed more easily from mulched soil. Hard-to-control weeds such as nutgrass and johnsongrass may come through the mulch layer but can be pulled more easily or covered by fluffing the mulch with a fork.