How deep should mulch be applied around trees?

Wood and bark chip mulch protects trees and shrubs from lawnmower damage. However, do not make “mulch volcanoes” around tree trunks by applying chips up against a tree’s trunk. 

Wet chips piled up against the trunk can cause bark problems and interfere with the natural trunk taper, making the tree more prone to wind throw.  Keep the mulch at the base of the tree and preferably back at least 6” from the trunk.   

Bark mulch mounded up around a tree trunk


bark mulch placed around the trunk flare at the base of a tree


Please, NEVER pile bark mulch around tree trunks!
photo credit: Gardens, Lawns, and Landscapes
Flickr CC BY-NC-SA 2.0

Bark mulch placed below and away from the trunk flare at the base the tree is healthier for the tree.
photo credit: OSU Master Gardener
Flickr CC BY-NC-ND 2.0