Although most roots tend to grow (and stay) underground, sometimes those belonging to trees can make their way to the surface. While this isn’t something you necessarily notice out in the woods (unless you’re walking on a trail and happen to trip over some), seeing tree roots emerge from your lawn is a different story.
Here’s what to do — and equally important, what to avoid — if you have visible tree roots in your lawn.
Why are tree roots visible in your lawn?
Officially, these are known as “surface roots,” and if they’ve emerged from underground and spread across part of your lawn they not only pose a safety hazard (providing something else for people to trip over), but they also make it difficult to cut your grass. So what’s going on with these roots, and why are they on the wrong side of the ground?
According to Diana Alfuth, a horticulture educator at the University of Wisconsin-Madison’s Agriculture Institute, most large, mature trees can develop surface roots, but it’s especially common in species like poplar, willow and silver maple.
Typically, most of a tree’s roots grow horizontally in the top four to 15 inches of the soil, allowing them to remain protected underground, but close enough to benefit from the oxygen that permeates the surface of the soil. But when the soil becomes compacted, heavy, or no longer drains effectively, the roots gradually move closer towards the surface.
“Each year a tree’s roots get thicker, just like the trunk does, and eventually they can break the surface and be visible in the lawn,” Alfuth writes. “Erosion of soil over a root system is another cause of surface roots.”
Don’t damage the tree’s roots
Avoid doing anything that will damage a tree’s roots, including:
- Attempting to dig them up
- Cutting, chopping, or pruning them
- Using a rototiller on them or the adjacent areas
- Running them over with a lawnmower or tractor
How to protect a tree’s roots
If you are adamant about reclaiming that area for your lawn, the key to making it possible is protecting the tree’s surface roots. One way to do this is to spread a shallow layer of topsoil around and over the exposed roots — enough so they’re covered by about a half inch of dirt.
Be careful not to cover the surface roots in too much soil, though — that can end up suffocating the tree, either damaging or killing it. And keep in mind that you’ll probably need to do this again in the future, as the tree’s roots will continue to get thicker every year and could make their way back up to the surface.
You can also stop trying to grow grass in that part of your yard, and cover the area in mulch or wood chips instead. Another option would be creating a clear border around the surface roots using larger rocks or bricks, and letting the roots do their thing.