Robust tree roots in a yard often create frustrating and costly issues for homeowners. These subterranean extensions primarily seek out oxygen and water, quickly becoming noticeable problems above ground. Common concerns include uneven lawn surfaces that pose a tripping hazard, damage to mowing equipment, and the lifting and cracking of concrete features like sidewalks, patios, and driveways. Root expansion can also impact the structural integrity of nearby built elements, leading to significant repair expenses.
Diagnosing the Root Issue
The first step in effective root management is correctly identifying the problem’s source and severity. Tree roots grow mostly horizontally and typically reside in the top 12 to 24 inches of soil, often extending far beyond the tree’s canopy. When diagnosing the issue, distinguish between surface roots in a garden setting and those encroaching on structures.
Observing the tree species is also necessary, as different trees have varying root aggressiveness and growth habits. Fast-growing species like willows, poplars, and silver maples are known for developing extensive, shallow root systems that cause surface and underground issues. Conversely, trees with naturally deeper root systems pose less risk to surface hardscapes. A thorough diagnosis involves noting the root’s proximity to structures and identifying if a root is merely a surface nuisance or a threat to foundations and utilities.
Strategies for Managing Surface Roots
Surface roots, typically exposed due to soil erosion or compacted soil, challenge yard maintenance and safety. While the temptation to simply cut these roots is strong, doing so can severely compromise the tree’s health and stability, since the majority of feeder roots are near the surface. Cutting a large root can introduce pathogens and destabilize the tree, making it prone to failure.
For roots less than one inch in diameter, limited, cautious pruning can be performed during the tree’s dormant season. This pruning should not exceed 15% to 20% of the tree’s total root system at one time. Roots two inches or larger should not be cut without consulting a certified arborist, as removing them poses a high risk to the tree’s survival.
A better approach for managing surface roots is to apply a thin layer of organic material over the exposed areas. Applying a two- to four-inch layer of wood mulch is the most recommended non-invasive method; it covers the roots, helps retain soil moisture, and reduces the need for mowing. Alternatively, a mixture of topsoil and compost can be layered over the roots, but this layer should be very thin—no more than a half-inch at a time—to avoid suffocating the root system by blocking oxygen exchange.
Protecting Foundations and Underground Utilities
Roots that threaten built infrastructure require a proactive management strategy to prevent expensive damage. Tree roots are not strong enough to break a sound pipe or foundation, but they exploit existing cracks or loose joints in search of water and nutrients found within sewer or water lines. Once inside a damaged pipe, the roots expand rapidly, leading to blockages and further damage.
A primary preventative measure is installing a root barrier, a physical shield made of high-density plastic or metal placed vertically in the soil. These barriers redirect root growth downward and away from the structure rather than blocking water or nutrients entirely. For maximum effectiveness, especially in expansive clay soils, a root barrier should be installed to a minimum depth of 30 inches; deeper installation, up to 48 inches, is often recommended for large trees.
When roots have already infiltrated a sewer line, professional methods are required to clear the obstruction. Hydro-jetting uses high-pressure water to mechanically cut and remove the roots. Chemical root inhibitors, such as copper sulfate, can also be introduced into the pipe to kill the invading roots, though their use should be considered carefully due to potential environmental effects. For roots near a foundation, any targeted root removal should be handled by an arborist who can determine the structural necessity of the roots before cutting them.
Future Planning and Tree Selection
The most effective way to avoid future root problems is through informed species selection and proper planting location. Trees known for developing invasive root systems, such as willows, elms, and certain maples, should be avoided near infrastructure. Instead, opt for species with contained or non-aggressive root habits, which are less likely to cause upheaval.
When planting new trees, site assessment is crucial. Calling the national “Call Before You Dig” number (811) to locate underground utilities is a required first step. Small- to medium-sized trees should be planted at least 10 to 15 feet away from underground lines, while large-maturing trees require 20 feet or more of clearance. Planting distance from a house or foundation should be based on the tree’s mature size, with large trees requiring a minimum of 20 feet of separation to allow for adequate root spread without structural conflict.