Did you know that a tree can actually strangle itself with its own roots?
1. Identify problem tree (it probably has a mulch volcano)
Despite the fact that everyone from homeowners to professional landscapers does it, mulching your tree so that the mulch covers the lower part of the trunk is a bad idea. You should be able to see the root flare, the point where the tree flares out to its main roots. And those large, main roots should be visible at the surface of the soil, or just an inch or two below it.
2. Remove the mulch volcano to expose the roots
We used an air knife: a compressor-driven blast of air that removes anything porous (i.e. soil) while leaving the roots completely intact. It’s fabulous, and we got fabulously dirty in the process.
3. Find problem roots
Trees that are planted too deeply or are mulched too high are prone to girdling roots. Adventitious roots form above the main root structure wherever the trunk is covered by soil (or mulch). Those roots grow upward. Once they hit air, they turn and start growing around the trunk, encircling it.
As the tree grows in diameter, it eventually hits the girdling root, which compresses the tree trunk. As a result, nutrients can’t flow correctly from leaves to roots and back, and the tree may also become unstable. Stem girdling leads to a decline in the tree’s health and an early death for the tree.
4. Remove adventitious and girdling roots
Using pruners, loppers, and saws, we removed any roots above the main root structure. When we ran into a particularly large girdling root that had grafted itself to other roots, we sawed through the root in a few places instead of trying to remove it completely. Compare the photos above and below to see the difference.
5. Mulch the tree correctly
Mulch should not cover the main roots or the root flare. Instead, we used the mulch to form a flat ring several inches away from the trunk. By making the sides of the ring sloped, we direct any rainwater that falls towards the roots. And don’t worry; those exposed roots will form bark in short order.