At what depth should trees and shrubs be mulched?

Mulching trees and shrubs at a depth of 2-4 inches is optimal for several reasons. This depth is sufficient to suppress weeds, conserve soil moisture, and regulate soil temperature without creating a barrier that restricts oxygen and water availability to the plant roots.

Mulch at this depth helps maintain an ideal balance, allowing for healthy root development while protecting against extreme temperature fluctuations. If the mulch is too shallow, it may not effectively prevent weed growth, while a depth greater than 4 inches can lead to excess moisture retention and potential root rot, as well as harboring pests. Therefore, a mulch layer of 2-4 inches combines the benefits of protection and support for the overall health of trees and shrubs.