Maintaining a uniform lawn where turf meets trees presents a challenge, as cutting grass close to the trunk risks damage that compromises the tree’s health. Integrated lawn care aims for a neat appearance without causing mechanical injury to the bark or disturbing the delicate root structure beneath the soil surface. Employing specific techniques and alternatives ensures both a manicured yard and the continued well-being of the trees.
Preparing the Mowing Zone
Before mowing, thoroughly inspect the area surrounding the tree to mitigate potential hazards. Removing debris like fallen branches or stones prevents them from being violently ejected by the blades, which is a significant safety concern. Cleared ground also allows for better visibility of the tree’s structure and any obstacles.
The most sensitive area is the root flare, where the trunk widens at the soil line. This area must remain exposed and protected from mechanical abrasion. Identify surface roots, which are common and easily damaged or scalped by a low-set deck.
Tree roots typically extend far beyond the canopy’s drip line. While avoiding the entire root zone is impractical, mark prominent surface roots with a temporary marker, like a small flag, to prevent contact with the mower. Setting the mower deck height appropriately high prevents scalping the soil above shallow root systems, which can stress the tree.
Safe Mower Operation Near Trees
When operating the main mowing machine near a tree, reduce the ground speed significantly to allow for greater control and precise maneuvers. A high-speed collision, even a glancing blow, can quickly strip bark, creating an open wound susceptible to pests and disease.
Instead of sharp turns, employ sweeping, gradual curves when circling a tree. This technique maintains momentum while keeping the mower deck at a consistent distance from the trunk, minimizing the risk of scraping the bark. The goal is to cut the grass without allowing any part of the machine to contact the woody tissue.
Maintaining a consistently high deck height protects the tree’s subsurface anatomy. Even if the turf appears level, the ground often rises slightly over the root crown or above surface roots. A lower deck height risks scalping the soil in these elevated areas, which can sever fine feeder roots. Scalping also severely compacts the soil, inhibiting nutrient and water uptake.
The weight of riding mowers and repeated passes can cause significant soil compaction directly over the tree’s active root zone. For mature trees, it is better to reduce the frequency of mowing directly under the canopy or to alternate the mowing pattern with each cut. This modification reduces pressure on the soil structure, promoting healthier root growth and better gas exchange.
Alternatives for the Tree Base
The immediate area at the base of the trunk, often called the no-mow zone, is inaccessible to the main mower deck. Using a string trimmer requires extreme caution because the high-speed line easily damages the thin bark of young trees. Repeated abrasion from the trimmer line can completely strip the outer layer of tissue, a process known as girdling, which interrupts the tree’s ability to transport sugars and water, often leading to death.
To use a string trimmer safely, the operator must hold the head parallel to the ground and use the lowest effective power setting. Trimming should be directed away from the trunk, only cutting the grass blades and avoiding contact with the bark entirely. For maximum protection, a physical barrier or a durable plastic guard can be temporarily placed around the trunk during trimming operations.
Creating a mulch ring is the preferred long-term solution for maintaining the tree base, as it eliminates the need for trimming in this sensitive area. Mulch suppresses grass and weeds, retains soil moisture, and helps moderate soil temperature fluctuations. The ring should extend at least three feet from the trunk, or to the tree’s drip line if practical, but must not touch the trunk itself.
Proper mulch application involves spreading a layer approximately two to four inches deep across the designated area. Leave a small, donut-shaped gap of several inches around the root flare to prevent “volcano mulching.” Piling mulch directly against the trunk traps moisture and creates an environment conducive to rot, insect infestation, and disease development at the bark line.