Exposed tree roots are a common landscape issue, presenting challenges like tripping hazards and interference with lawn maintenance. While the appearance of roots above the soil line may seem like a problem requiring a quick fix, improper covering methods can severely compromise a tree’s health and stability. The goal is to safely integrate these roots back into the landscape without suffocating the tree or creating an environment conducive to rot and disease. Effective solutions focus on mimicking natural forest floor conditions to protect the roots while ensuring they maintain access to air and water.
Why Tree Roots Become Exposed
Tree roots naturally grow close to the soil surface because the majority of the oxygen they require is found within the top 4 to 15 inches of the ground. When soil becomes compacted, the lack of air pockets forces roots even closer to the surface in search of oxygen. Certain species, such as maples, poplars, and willows, are genetically predisposed to having shallower root systems that are more likely to surface as they mature.
Soil erosion caused by heavy rain, wind, or surface runoff can gradually wash away the protective layer of topsoil. As the tree grows, its roots also increase in girth, which physically pushes them up and through the soil surface.
Covering Methods That Harm Trees
A common, yet damaging, mistake is piling a heavy amount of regular garden soil directly over the exposed root zone. Adding more than one or two inches of dense soil can suffocate the fine feeder roots by blocking the necessary exchange of oxygen and carbon dioxide. This deep covering can lead to root death, decay, and a decline in the tree’s overall health.
Another destructive practice is cutting or shaving the visible surface roots to eliminate tripping hazards. Severing even moderately sized roots compromises the tree’s stability, as the root system provides structural anchorage. Furthermore, a fresh cut creates an open wound, which serves as a direct entry point for fungal diseases, decay organisms, and insects.
Hardscaping over the root zone, such as paving with concrete or laying thick layers of stone, restricts the tree’s access to air and moisture. These materials severely compact the soil, preventing the uptake of water and nutrients. Using hard, non-porous materials ultimately starves the roots and causes long-term damage to the tree.
Safe Techniques for Root Coverage
The most recommended technique for covering exposed roots is the proper application of organic mulch. Shredded wood chips or pine bark should be spread in a layer between two and four inches deep over the affected area. This layer insulates the roots from temperature extremes, retains soil moisture, and protects the roots from physical damage.
It is important to avoid the practice known as “mulch volcano,” where the material is piled high against the tree’s trunk. Mulch should be kept several inches away from the trunk flare to prevent moisture buildup against the bark. Continuous dampness on the trunk can lead to fungal growth, pest infestation, and rot at the tree’s base.
Using Specialized Soil
For areas where mulch is impractical, a very thin layer of specialized, lightweight, porous topsoil or compost mix can be applied. This material should be broadcast gently, covering the roots by no more than one to two inches. This minimal depth allows for air and water penetration while offering a slight cushion.
Planting Groundcovers
Planting shallow-rooted groundcovers offers another permanent solution that helps stabilize the soil and prevent future erosion. Suitable choices include shade-tolerant varieties like hostas, ferns, periwinkle, or ajuga, which thrive under the tree canopy. When installing groundcovers, carefully hand-dig small pockets between the roots to avoid damage, rather than disturbing the entire area with a rototiller.
Ongoing Maintenance and Prevention
After covering the roots, regular monitoring of the area is necessary to ensure the tree’s health. The mulch or specialized soil layer should be checked periodically and refreshed as needed to maintain the recommended depth. Allowing the material to decompose naturally enriches the soil structure.
Adjusting irrigation is another step, as surface runoff can quickly erode newly placed covering material. Deep, infrequent watering encourages the tree’s roots to grow downward, promoting a more stable root system. Avoiding excessive foot traffic directly over the covered roots is beneficial, as repeated pressure causes soil compaction, which is a primary driver of root exposure.