Mulching is one of the most beneficial things a property owner can do to protect the health of a tree. But some people are taking it too far and over mulching, which can damage trees and other plants.
Make sure the mulch bed is no more than 2-4 inches deep. In addition, make sure mulch does not get mounded high around base of the tree, creating a ‘mulch volcano’. These two practices can lead to:
1. Insect and disease problems
2. Excess moisture in the root zone
3. Nutrient deficiency or toxicity
4. Creation of a habitat for rodents who chew bark or girdle trees
5. Promotion of surface roots in maple trees, which can grow into the tree trunk and girdle it
Here are some tips from the International Society of Arboriculture
For well-drained sites, apply a two to four inch layer of mulch. If drainage problems exist, use a thinner layer.
If mulch is already present, check the depth. Do not add mulch if there is already a sufficient layer (2 to 4 inches) in place. Instead, rake the old mulch to break up any matted layers and refresh the appearance
Avoid placing mulch against the tree trunks. If mulch is already piled against the stems or tree trunks, pull it back several inches so that the base of the trunk and the root crown are exposed.
Spread mulch out to the tree’s drip line or beyond if possible.
Photo Caption: Mulch is piled too high and too close to the tree trunks in the photo above – forming what we call a Mulch Volcano.