How Too Much Mulch Can Kill Your Tree
May 21, 2015
Despite all the heavy rain we’ve been having this spring, summer is just around the corner. Most likely, the rainfall will decline and intense heat will again impact our trees and landscapes. Mulching your landscape beds and trees is a great way to conserve moisture in the soil and moderate soil temperature. You’ll find that if you don’t mulch your landscape before the onset of summer, plants typically struggle to make it through the heat. Mulch also has many other great benefits.
Benefits of mulch and why you should add it to your trees, shrubs and other landscape plants:
- Mulch regulates soil temperatures so roots stay cool in summer and keep warm in winter.
- Want to water less? Mulch reduces evaporation from the soil so you water less, especially through summer.
- Landscape looking out of sorts? Mulching around trees, perennials, shrubs and planted containers will give everything a refined and finished look.
- Mulch is a weed suppressant! It cuts down on weed germination.
- As the mulch breaks down over time, it releases beneficial nutrients into the soil.
Don’t Over-Do It
If your tree looks like the photo below, your tree is over-mulched! Many homeowners, and even landscape maintenance companies, will add big piles of mulch around the base of tree in an effort to conserve water. In reality, all that mulch piled up against the tree bark can cause many more problems than it solves. Too much mulch not only suffocates feeder roots located near the soil surface, but it also holds moisture against the base of the trunk, creating the perfect conditions for fungal diseases and decay.
How to mulch your tree: Never pile the mulch against the tree trunk.
- If you have lawn grass growing under the tree, we recommend removing any grass within a 3- to 10-foot area depending on the size of your tree.
- Add mulch to the base of your tree within this 3- to 10-foot area under the tree.
- Put down a natural mulch 2- to 4-inches deep within the circle.
- Keep the mulch from touching the trunk of the tree.
- For newly planted trees, you can create a “berm” to hold water by mounding a few extra inches of mulch in a donut shape around the drip line.
We recommend refreshing the mulch around your trees in both in late-spring and fall.