I’ve Got Surface Roots! What Can I Do?

Roots that appear on the surface of our lawns frequently create headaches and problems for us. These shallower roots grow into the nutrient rich, moist, and oxygen rich layers closest to the soil surface. Heavy clay topsoil poses the greatest problem. As clay becomes compacted, the pores that allow water and oxygen penetration become compressed and ineffective. Clay soils do not drain well and exclude oxygen essential for healthy root growth, forcing roots to the surface where oxygen is more plentiful.

Any tree can develop surface roots when growing in heavy clay soil.  Some maples, sycamores, willows and ash have shallow growing root systems. 

Exposed roots create a maintenance challenge and trip hazard. In addition, foot traffic and splashing water erode some of the soil away, making them even more visible and problematic.

Surface roots can make mowing difficult and are frequently damaged, which can lead to root decay. Roots are denser near the trunk and compete for water and nutrients with the turf grass growing above. Coupled with poorer light penetration, the grass may become thin and, in some instances, die out. This is a very common occurrence under purple leaf Norway maples.

Several common, but ill-advised, approaches have been used to remedy these situations. These include cutting or grinding the roots, adding a heavy layer of topsoil to cover the roots and/or building a planter around the tree and filling it with soil. Cutting roots destroys the pathway needed for water and nutrient transport to the tree and in some instances affect tree stability under high winds. Adding heavy soil, even a couple of inches, can slowly smother the trees absorbing root system.

The best solution for bothersome surface roots is to cover them with mulch. Woodchip mulch has been found to benefit trees the most. A 2–3-inch layer is recommended. For best results create a mulch ring that extends out to the dripline of the tree. Not only can this be aesthetically pleasing, it provides an improved growing environment for the tree and keeps the mowers and weed eaters away.

Proper root pruning is possible when done by a professional arborist. Be sure any mitigation method does not compromise tree health and increase the risk of tree failure.