Much to the dismay of homeowners, landscape trees sometimes grow roots on top of the surface of the lawn or possibly even buckle sidewalks and driveways. These surface roots can be quite a nuisance to lawn mowers and running feet.
There are several reasons why the roots come to the surface. Some tree species seem to be more prone to surface roots than others, most notably silver maple, poplar and willow. But almost any large, older tree will produce some surface roots. The notorious species are likely just fast-growing species that bring the problem to the surface faster than others.
Although trees do send some roots down deep for moisture and stability, most tree roots tend to grow much more shallowly than most people think–usually only 4-8 inches deep. Just as the trunk of the tree grows in girth with age, so do the roots. So over time, some of the shallow, older roots of the tree will naturally enlarge to the surface. Sometimes, roots become visible due to erosion of the surface soil.
Root barriers made of either plastic or fabric have been tried with some degree of success in slowing the development of surface roots. However, over time, most root barriers will fail, either through cracking of the plastic or roots growing up and over the barrier into the decorative top mulch.
Once the roots appear on the surface, there is little that can be done to remedy the situation, without substantially damaging the tree. You can prune off the visible roots, but the damage to the cut roots and the fine feeder roots surrounding the area can harm or even kill the tree. Pruning the roots should be confined to situations where the roots are breaking up sidewalks or driveways.
Some homeowners have tried a temporary solution by applying a shallow, 1-inch layer of good-quality soil mix and then replanting the grass. However, it isn’t long before roots will reappear as they continue to grow in girth. A more permanent solution would be to replant the affected surface area with a taller ground-cover type plant that will not need mowing.
The best remedy for surface roots is to choose the proper plants for the situation. But if you already have a large, old tree with surface roots that you don’t want to lose, you may just have to learn to accept its intrusion into the lawn.