Large tree roots pushing up through a lawn or path create a common dilemma for property owners, presenting tripping hazards and interfering with maintenance. The immediate question is whether these exposed roots can simply be cut away. Cutting exposed tree roots is highly risky and should be avoided, as it can severely compromise the tree’s health and stability. The viability of cutting a root depends entirely on its size, its proximity to the trunk, and its role within the tree’s underground structure.
Understanding Tree Root Anatomy and Function
A tree’s underground network consists of two main types of roots, each with a distinct function. The fine, thread-like structures are the absorptive or feeder roots, which are responsible for the uptake of water and minerals from the soil. These roots are numerous and are typically concentrated in the top 18 inches of the soil, where oxygen and moisture are most available.
The larger, woody structures are the structural or brace roots, which are most often seen exposed above ground. Structural roots anchor the tree firmly in place, providing the mechanical support necessary to withstand strong winds and gravity. These roots also contain the vascular tissue, which transports water and nutrients back to the trunk and canopy.
Cutting a structural root is far more damaging than cutting a feeder root, as it immediately affects the tree’s stability and transport capacity. The mature root system works as a single unit to maintain the tree’s massive above-ground structure. The loss of a significant structural root can leave the tree vulnerable to falling over, sometimes years after the cut, especially during severe weather.
Determining If a Root Can Be Safely Cut
The decision to cut an exposed root involves a careful risk assessment based on the root’s size and location relative to the tree trunk. Arborists use a key guideline focusing on the root’s diameter; anything larger than 1 to 2 inches is generally considered too risky to remove. Cutting a root larger than this range can lead to significant structural weakening or long-term health decline.
Proximity to the trunk is the most important factor, defining the tree’s “Danger Zone.” This critical area is the structural root plate, which extends outward three to five times the trunk’s diameter. Roots within this zone are the tree’s primary stabilizers, and cutting them dramatically increases the probability of the tree failing, particularly on soils that are shallow or poorly drained.
When a root is cut, the resulting wound becomes a direct entry point for decay-causing microorganisms, such as fungi. This decay can travel inward, weakening the root collar and potentially compromising the entire root system over time. Removing a large root may also cause sufficient stress to reduce the tree’s ability to transport resources, leading to canopy dieback or increased susceptibility to pests and diseases. Consulting a certified arborist is strongly recommended before attempting to cut any root close to the trunk or exceeding two inches in diameter.
Non-Invasive Solutions for Exposed Roots
Since cutting large exposed roots poses significant risks, the safest approach is to manage the surface roots non-invasively. The most common and effective method is to create a mulch bed over the exposed area, which protects the roots from foot traffic and lawnmower damage. Organic mulch, such as wood chips or shredded bark, should be applied in a layer 2 to 4 inches deep.
It is important to keep the mulch away from the trunk itself, creating a “mulch donut” to prevent moisture buildup and disease entry. This layer mimics the natural forest floor, allowing oxygen and water to penetrate while insulating the roots from temperature extremes. For minor root exposure, a thin layer of topsoil, no more than 1 to 2 inches deep, can be added and seeded with a shade-tolerant ground cover.
For areas with high foot traffic, adjusting the hardscaping is a practical solution. This can involve rerouting a path or building a deck section that spans over the root. Ensure the construction remains raised and does not compact the soil or restrict air and water flow to the root zone. In cases where a root must be addressed due to infrastructure conflicts, professional arborists can install a root barrier to redirect growth or use specialized tools for selective root pruning over several seasons.