Why Piling Soil Over Exposed Tree Roots Causes Fatal Damage
Adding thick layers of topsoil to cover surface roots can suffocate trees by restricting oxygen.
1The Danger of Soil
Many homeowners attempt to tidy lawns by covering exposed tree roots with thick layers of topsoil. Experts from the University of Kentucky and the University of Wisconsin-Madison warn this practice is dangerous. Adding deep fill over the root zone effectively suffocates the tree, often leading to significant health decline or death.
2Why Roots Surface
Tree roots do not naturally grow deep into the ground. Most roots spread horizontally within the top 4 to 15 inches of soil to access necessary oxygen. In compacted or poorly drained soil, roots are forced even closer to the surface. Erosion can also wash away topsoil, leaving these vital structures exposed.
3Risks of Root Pruning
Cutting or grinding off visible roots is considered the most damaging action a homeowner can take. Pruning these roots or repeatedly hitting them with lawnmower blades can severely compromise the tree's health. These roots are essential for survival, and damaging them disrupts the tree's ability to absorb water and vital nutrients.
4Proper Soil Management
If you must use topsoil to cover roots, keep the layer extremely thin, ideally half an inch or less. Applying more than this amount risks cutting off the oxygen supply that roots require to function. This minimal application helps maintain a tidy appearance without burying the root system under suffocating weight.
5Benefits of Wood Mulch
Experts recommend replacing grass around the tree base with a 2- to 3-inch layer of shredded wood or chips. This mulch provides a protective cushion for the roots while allowing for better gas exchange. Extending this mulch ring as far as the canopy's dripline creates a healthier environment for the tree.
6Strategic Mulch Application
When applying mulch, keep it several inches away from the tree trunk to prevent bark rot. Avoid the practice of volcano mulching, where mulch is piled high against the trunk. Instead, maintain a flat, wide ring that protects the root zone while ensuring the trunk remains dry and free from decay.
7Planting in Small Pockets
For those seeking aesthetic color, avoid tilling the entire area under the tree canopy. Instead, hand-dig small planting pockets between the roots to accommodate shade-loving perennials or groundcovers. This method preserves the integrity of the root system while allowing for creative landscaping that enhances the visual appeal of your backyard.
8When to Consult Professionals
If significant fill has already been added or the tree shows signs of thinning, branch drop, or dieback, consult a certified arborist. Arborists can determine if the fill needs removal and how to proceed without causing further injury. They are also essential for managing roots that lift sidewalks or driveways safely.
Original article: Trendir — Why Piling Soil Over Exposed Tree Roots Causes Fatal Damage