Exposed tree roots, often called surface roots, are a common sight in mature landscapes that cause concern for property owners. These visible root structures extending above the soil surface are a natural part of a tree’s growth, but they present potential issues for both the tree’s health and the surrounding property’s integrity. While a certain degree of root flare exposure is normal, extensive surface rooting can signal underlying environmental problems or become a maintenance nuisance. Understanding the reasons behind this phenomenon is the first step toward managing it safely and effectively.
Primary Reasons Roots Grow Near the Surface
Tree roots primarily grow where they can find the necessary resources for survival: water and oxygen. Contrary to the common belief that roots grow deeply, the vast majority of a tree’s root system, including the fine feeder roots responsible for nutrient and water absorption, resides within the top 12 to 18 inches of soil. This shallow growth pattern is an adaptation to access the oxygen that is often scarce in deeper, poorly aerated soil layers.
Environmental conditions often exacerbate this natural tendency, forcing structural roots closer to the surface. Soil compaction, frequently caused by heavy foot traffic or construction equipment, dramatically reduces the oxygen and pore space available in the soil, compelling roots to grow upward. Furthermore, the gradual process of soil erosion, where wind, rain, or runoff washes away topsoil, can expose roots that were previously covered and developing normally. Certain tree species, such as maples, willows, and poplars, also possess a genetic predisposition to develop a more naturally shallow and aggressive root system.
Assessing the Damage to Trees and Property
The presence of exposed roots poses distinct threats to the health of the tree itself. Surface roots are highly vulnerable to mechanical damage from routine lawn maintenance, such as being nicked by lawnmowers or string trimmers, which creates entry points for pests and disease pathogens. Additionally, the lack of soil insulation makes these roots susceptible to extreme temperature fluctuations, particularly the intense heat of summer and the freezing temperatures of winter. This temperature stress can significantly hinder the tree’s ability to absorb water and necessary nutrients.
The consequences for property and safety are often what prompt homeowners to seek solutions. Extensive surface roots can lift and crack hardscapes like sidewalks, driveways, and patios as the roots thicken and expand over time. This lifting creates uneven surfaces that are significant tripping hazards, raising potential liability concerns for property owners. While foundation damage is a common concern, roots typically only exploit existing cracks in foundations in search of moisture, rather than causing the initial structural breach themselves. They also make it difficult to maintain a healthy lawn underneath the tree canopy due to resource competition and the inability to mow around the obstacles.
Safe Strategies for Managing Exposed Roots
The most damaging mistake when dealing with exposed roots is cutting them, as this severely reduces the tree’s stability and its capacity to absorb resources. Removing even a single large structural root can compromise the tree’s anchorage and increase the risk of it falling during high winds. Piling excessive amounts of new soil over the roots is also harmful because it can suffocate the root system by blocking the necessary oxygen exchange.
A safer and more effective strategy is to protect the exposed roots with a layer of organic mulch. Applying a layer of shredded wood chips or bark mulch, typically between 2 to 4 inches deep, insulates the roots from temperature extremes and retains soil moisture. It is important to keep the mulch ring pulled back several inches from the trunk to prevent moisture buildup and decay near the root flare. Where a lawn cannot be maintained, planting a root-tolerant, shallow-rooted ground cover is another non-invasive option that provides an aesthetically pleasing cover and further stabilizes the soil.