Mulch mountains in tree circles is a disaster that just won’t go away. I had written a short blog post about this in 2015. Fast forward to February 8, 2017. Sitting in on a lecture by Dr. Bruce Fraedrich of Bartlett Tree Experts, I was reminded of this issue again.
According to Dr. Fraedrich, he has been talking about this issue for over 25 years! The issue isn’t going away. In his presentation he showed one tree well mulch mountain with his child; the other photo was with his grandchild. Point made.
Why mulch?
There are many benefits to putting mulch into tree wells. If it’s installed properly. Four key benefits are listed below.
- Water conservation.
- Weed reduction, assuming we install the mulch at a decent depth. Going light on mulch can actually encourage weeds to grow.
- Improved soil quality.
- Enhanced plant growth.
The key issue
The installation workers, presumably landscapers, piled the mulch way over the root flare. It looks pretty. But it’s bad for the tree. Why?
Piling mulch against the trunk of trees and shrubs creates a dark, moist, low oxygen environment to which above-ground tissues are not adapted. See the picture below. Fungal diseases require precisely this kind of moist environment to grow and reproduce; and to eventually enter the plant.
Opportunistic pests are also more likely to invade a plant whose bark is wet due to excessive mulching.
It is also possible to get adventitious roots developing in the moist zone. These roots grow and circle the tree potentially causing girdling.
Solutions
Extend the existing tree circle out farther, if possible. Then remove all excess mulch from the trunk and use it in the extended circle zone. If the circle can not be enlarged then still remove the excess mulch and use it elsewhere.
The look we want is donut-shaped. This will protect the soil environment and above-ground tissues.
Include this work in your regular landscape maintenance. Periodically check your tree wells and remove any excess mulch from tree trunks. Train all staff.
Coordinate with installers. Sometimes they are young labourers with strict time guidelines. Sometimes companies send people to blow mulch in. They need good directions and supervision.
