Exposed tree roots are a common landscape concern for homeowners. They surface either through natural thickening as the tree matures or due to erosion washing away the top layer of soil. While they create tripping hazards and interfere with lawn maintenance equipment, managing them safely is necessary to maintain the tree’s health and landscape integrity. This guide provides actionable steps for dealing with exposed roots without causing harm.
Understanding the Sensitivity of Exposed Roots
Tree roots grow near the surface, typically within the top 4 to 12 inches of soil, where oxygen, water, and nutrients are most readily available. These shallow roots are the tree’s primary mechanism for survival. The finer, non-woody roots near the surface, referred to as absorbing roots, are responsible for nearly all water and mineral element uptake. When exposed, they are highly vulnerable to physical damage from foot traffic, lawn equipment, or sun scald. Damage to these roots can hinder the tree’s ability to absorb necessary resources, leading to dieback or a general decline in health.
Actions That Cause Severe Tree Damage
Attempting quick fixes for exposed roots often results in severe, long-term damage to the tree. One destructive action is cutting or severing the roots to clear a path or level the ground. Removing large structural roots, especially those over two inches in diameter or close to the trunk, compromises the tree’s stability, making it susceptible to falling during strong winds. Even small cuts create open wounds, providing easy entry points for pests, fungal diseases, and rot. Cutting off a portion of the root system also immediately reduces the tree’s ability to absorb water and nutrients, which can shock the tree and cause dieback.
Another common but harmful practice is adding a significant layer of new soil over the exposed roots. Adding more than two or three inches of heavy topsoil will suffocate them. Tree roots require oxygen for respiration, and a deep layer of soil compacts the ground, driving out the air pockets they need to breathe. This lack of oxygen can lead to root rot and tree decline.
Lastly, using heavy machinery like tillers or repeatedly driving over the root zone compacts the existing soil. This compaction destroys the fine absorbing roots and forces new roots to grow even closer to the surface in search of air and water, exacerbating the original problem.
Safe and Effective Management Strategies
The safest approach to managing surface roots involves protective measures that do not restrict air flow or cause physical damage. Applying a layer of organic mulch is the most widely recommended and tree-friendly solution. A layer of shredded wood chips or bark, spread two to three inches deep, insulates the roots from temperature extremes and retains soil moisture. It is essential to use the “donut method,” keeping the mulch several inches away from the tree’s trunk flare to prevent moisture buildup that can lead to collar rot. Mulch also eliminates grass in the root zone, reducing the need for mowing and protecting the roots from equipment damage.
Instead of trying to grow grass, homeowners can plant low-growing, shallow-rooted groundcovers that tolerate shade. Plants like periwinkle, sweet woodruff, or creeping Jenny can mask the roots and help stabilize the soil without competing heavily for resources. When planting, hand-dig small holes carefully between the roots, avoiding the use of a rototiller in the root zone.
Adjusting lawn maintenance practices is often necessary to prevent accidental damage. Raising the mower deck to its highest setting when near the roots, or converting the area under the tree’s canopy entirely to a “no-mow” zone, prevents the blades from scraping or wounding the exposed roots. For high-traffic areas, installing stepping stones or a path away from the trunk can redirect foot traffic, reducing soil compaction and physical trauma to the roots. When exposed roots are causing significant structural problems, such as lifting a patio or cracking a foundation, a certified arborist should be consulted to assess the situation before any action is taken.