During the summer this improves both root growth and nutrient availability. Winter mulches reduce the risk of root damage. Soils are improved with organic mulches as lower layers decompose and become incorporated into the soil. At the end of the growing season, organic mulches can be tilled into the soil to further increase the organic-matter content. Finally, mulches impart a neat, trim look to gardens, reduce the incidence of mud-splashed flowers and vegetables after heavy rains, and decrease the frequency of vegetable rot caused by soil contact.
Mulches do have some disadvantages.
Mulch and moisture around newly emerging seedlings or perennials can provide an ideal environment for diseases, such as damping-off or crown rot. The potential of disease is increased by long periods of rain. Diseases may overwinter in the mulch. Insects and rodents, who find it an attractive habitat, can cause plant damage. These problems can be minimized by avoiding direct contact between the plants and the mulch.