How much mulch should be applied and how often?

The recommended depth for mulch varies depending on the material and purpose. For most organic mulches like wood chips or bark, a layer of 2-4 inches is ideal for vegetable gardens, flower beds, and around trees and shrubs. Finer mulches like shredded leaves or straw may only need 1-2 inches. According to the [University of Maryland Extension](https://extension.umd.edu/hgic/topics/mulching-trees-and-shrubs), mulch should be replenished annually to maintain the proper depth as it decomposes. For inorganic mulches like gravel or rubber, a depth of 2-3 inches is typically sufficient, and they don’t need to be replenished as often.