Tree roots extend far beyond the canopy seeking water and nutrients, often conflicting with infrastructure like sidewalks, driveways, and utility lines. While the root system is necessary for stability and health, intervention is sometimes required to protect property. Safely cutting a root involves careful preparation and precise execution to ensure the tree remains stable. Approach root removal with caution, recognizing that any cut poses a risk to the tree’s overall well-being.
Pre-Cutting Assessment and Safety Guidelines
Before disturbing the soil, assess the tree’s health and the root’s importance. The Critical Root Zone (CRZ) is the minimum area around the trunk that must remain undisturbed for the tree’s survival. To estimate the CRZ radius, measure the trunk diameter at \(4.5\) feet above the ground, convert it to inches, and then multiply by \(12\).
This calculation identifies the area closest to the trunk where root removal is most dangerous. Cutting roots within three to five times the trunk diameter is high-risk and compromises structural support. When pruning is necessary, the goal is to remove the minimum root mass. Arborists advise against removing more than \(25\) percent of the entire root system, as this increases the risk of tree decline or failure.
Consider the size of the root, as larger roots provide more structural support and transport capacity. Avoid cutting any root greater than two inches in diameter. Before excavation begins, contact the local utility notification center (like \(811\) in the United States) to mark all underground utility lines. This prevents damage to pipes and cables that could be confused with tree roots during digging.
Practical Techniques for Root Cutting
Exposing the root for a clean cut requires techniques that prioritize minimal damage to the surrounding root network. Traditional shoveling can tear or damage the bark of remaining roots, creating entry points for disease. Arborists prefer pneumatic excavation tools, or air-spades, which use high-pressure air to break up soil without harming delicate root tissue.
For homeowners performing manual work, careful hand-digging with a trowel or small spade is the recommended method for exposing the root. Once exposed, make a clean, precise cut using sharp, sterilized tools such as bypass pruners, loppers, or a root saw. Avoid dull or blunt instruments because they crush the tissue, leaving a jagged wound susceptible to decay.
The cut should be made perpendicular to the root’s length, severing it as far from the trunk as possible, ideally at the boundary of the excavation area. Whenever possible, position the cut immediately next to a smaller, healthy lateral root branching off the main root. Cutting back to a lateral root encourages the tree to compartmentalize the wound and redirect growth away from the problematic area.
Long-Term Strategies for Root Management
Cutting a root does not prevent the tree from regenerating a new root system that may grow back toward the water or nutrient source. The long-term solution involves installing physical root barriers immediately after the cut to deflect future growth. These barriers, often made of high-density polyethylene (HDPE), must be installed deep enough to be effective, typically \(30\) to \(36\) inches deep.
The barrier should be placed parallel to the structure, such as a sidewalk or foundation. It must not completely encircle the tree, as this can destabilize the root plate. The barrier acts as a linear wall, guiding new root growth downward and away from the protected area. The top should sit slightly above the soil line to prevent shallow roots from growing over it.
In areas where roots lift pavements, alternative construction methods are often better than repeated cutting. Flexible paving materials, such as rubber mats or specialized asphalt, absorb movement without cracking, accommodating minor root growth. Another structural solution is bridging the footpath using pier and beam construction to elevate the walkway over the root zone, allowing roots to grow beneath without obstruction.
Following root pruning, the tree requires extra care, including consistent watering and the application of mulch to conserve soil moisture. This helps the tree recover from the stress of root loss. Monitor the tree for signs of decline, such as wilting leaves, canopy dieback, or suckers growing from the base.