Cypress knees, scientifically known as pneumatophores, are unique woody projections that grow vertically from the roots of bald cypress trees, often emerging above the soil or water line. These structures frequently become a nuisance for homeowners, creating tripping hazards across lawns and complicating mowing. Their presence prompts many to seek removal options, as they disrupt smooth surfaces and can damage lawn equipment. This article explores the options available for dealing with cypress knees, ranging from physical removal to safer, long-term landscape management.
The Biological Purpose and Risk of Removal
Cypress knees are typically associated with trees growing in swampy or frequently saturated soil conditions. While their function has been debated for decades, current scientific understanding points to them assisting the tree’s survival in wet environments. One theory is that the knees act as pneumatophores, facilitating gas exchange by allowing oxygen to diffuse to the submerged root system. Other research suggests they may provide mechanical support in unstable, soft substrates or serve as sites for carbohydrate storage.
Attempting to remove these structures introduces a risk of stressing the tree, especially if the tree relies on them for stability or gas exchange. Cutting or grinding a knee creates an open wound, which can become an entry point for wood-decaying pathogens or insect pests. Arborists recommend caution; while a healthy tree may tolerate the removal of a few distant knees, aggressively targeting many knees or those close to the trunk can compromise the tree’s health and vigor. Consulting with a certified arborist is advisable before undertaking any major removal.
Techniques for Physical Removal
For homeowners determined to eliminate the physical protrusion, the most common method is careful cutting. This technique involves exposing the knee a few inches below the soil level and making a clean, horizontal cut. Using a sharp pruning saw or reciprocating saw blade, the knee should be severed approximately one to two inches beneath the surface of the ground. It is important to make a smooth cut rather than chopping or tearing the wood, which minimizes the wound size and promotes faster healing.
A significant advantage of this method is that bald cypress trees do not typically re-sprout root suckers from the wound site. While the knee itself will not regrow, the root system may produce new knees nearby over time. For larger, more established knees, a mechanical stump grinder may be used to reduce the wood to below-grade level. Caution is advised when using a grinder, as the vibrations and cutting action can inadvertently damage the main supporting root system of the tree.
To maximize the tree’s recovery and minimize the chance of infection, physical removal should be timed for the dormant season, such as late winter. This period sees reduced activity from insects and fungal spores that might take advantage of the freshly exposed wood. After the knee is cut or ground down, the resulting hole should be immediately refilled with soil to protect the exposed root.
Strategies for Managing and Concealing Cypress Knees
An alternative to removal is to adopt landscaping strategies that safely manage and conceal the knees without damaging the tree. Instead of raising the soil level significantly, which can suffocate the tree’s roots, a light layer of organic mulch or pine straw can be applied around the base. This material helps to obscure smaller knees and creates a softer surface for pedestrian traffic, while also improving the soil environment. However, adding more than a few inches of soil or mulch is not recommended, as this can negatively impact the tree’s health.
Creative landscaping integration can transform the knees from obstacles into natural design features. The knees can be used as unique, organic borders within a garden bed, or they can be surrounded by groundcover plants that tolerate moist, shaded conditions. Selecting low-growing plants like ferns or certain perennial flowers can effectively hide the lower portion of the knees while blending them into the overall aesthetic.
For areas where knees interfere with lawn maintenance, modifying the mowing routine is a simple solution. This may involve stopping the turfgrass a safe distance from the tree and establishing a mulch bed, allowing the knees to exist in a dedicated, no-mow zone. Alternatively, replacing the grass entirely with a non-mow groundcover in the affected area eliminates the risk of equipment damage and provides a continuous, softer surface.