By Angie Naughton, Denton County Master Gardener Association
Caring for oak tree root systems that are exposed on top of the soil is important for the tree’s health while adding beauty to the landscape.
The tree roots that come to the surface of the soil provide the root systems with oxygen. Several conditions create an increased need for root zone oxygen including heavy clay soils, compacted soils, lack of moisture down deep into the roots, and the tree’s root flare buried too deeply.
The root flare is the area where the root system comes out of the tree trunk and provides the root systems with oxygen. Anything covering the root flare, including soil, mulch, and decorative rock, must be removed to expose the root flare and return the tree to a healthy state.
Once these obstructions to the root flare are removed, check the root zone for girdling roots that are growing in a circle rather than straight out from the tree. Circling roots are much less stable and are more likely to result in the tree uprooting during heavy rain and high wind.
They also literally strangle the tree, preventing the tree from being able to transport water and nutrients, leading to defoliation, branch dieback, and splitting bark.
This issue can be corrected in established trees using an air spade to expose the roots and pruning the problem roots. Assessing the tree’s root system and making any corrections is best done by a certified arborist.
Check the soil around the tree for compaction by pushing a screwdriver into the soil; if it doesn’t go down six inches easily, the soil around the tree may be compacted and not able to hold moisture.
To improve the landscape’s beauty, add groundcover plants such as Liriope, Asian Jasmine, and Asparagus Fern around the base of the tree. Plan to start with small plants that don’t require digging large holes in the exposed root area.
For more information about gardening in North Texas see dcmga.com/north-texas-gardening