Surface Roots in the Lawn: Cover, Cut or Live With Them

Under a big live oak in Edgewater or Port Orange, the lawn eventually gives up. Roots come up through the grass, the mower scalps them, the grass dies in the shade anyway, and what is left is bare sand, roots and a trip hazard. The homeowner wants to know if the roots can be cut.

The honest answer is that some can, most should not, and there is a better solution that costs less than a root job and does not put the tree on the ground.

Why roots surface

Tree roots are shallow by nature. The majority of a tree's root system is in the top foot or two of soil, because that is where the oxygen is. In Florida sand with a high water table, it is even shallower.

On top of that, roots grow in diameter every year, just like the trunk. A root that was buried at four inches when the tree was young is a foot across at maturity, and most of it is above the ground it started in. Add erosion of the topsoil, mower damage that thins the grass and speeds the erosion, and you get a yard full of exposed roots.

Surface roots are not a sign of a problem with the tree. They are what a mature tree looks like.

Why cutting them is a bad idea

The big roots near the trunk are structural. They hold the tree up. Cutting one within a few feet of the trunk removes a significant share of the anchorage on that side, and the effect is not immediate. It shows up in the next storm, when the tree fails toward the side that was cut, or three years later as decline as the tree loses the feeder roots beyond the cut. We laid this out in Root Pruning Before Construction.

Cutting a large surface root also opens a wound at ground level, where decay fungi are most active, into the part of the tree least able to wall them off.

If a specific root has to be cut for a hardscape reason, the rules are: the smaller the root, the farther from the trunk, the fewer of them, and clean cuts with a saw rather than a backhoe. An arborist should make that call on site.

What actually works

Mulch

The single best fix. A layer of mulch two to four inches deep over the root zone, out to the drip line or as far as you can stand it, covers the roots, protects them from the mower, retains moisture, and eliminates the losing battle of trying to grow turf in oak shade. Keep the mulch pulled back from the trunk itself; see Mulch Volcanoes and Buried Root Flares for what happens when it is piled against the bark.

Wood chips from tree work are ideal for this. If we are pruning or removing on your property, ask for the chips.

Shade-tolerant groundcover

Where you want something green, plant a groundcover that tolerates shade and root competition rather than turf. Asiatic jasmine, liriope, ferns and mondo grass all do well under oaks in our area and never need mowing over the roots.

A shallow topdressing, carefully

You can add a thin layer of soil (an inch or so) over exposed roots, once, to smooth the surface and let grass or groundcover establish. Do not bury the roots under several inches of fill. Roots need oxygen, and burying them suffocates the tree slowly. A grade change is one of the most common ways a mature tree gets killed. See Why Trees Die Three Years After Construction.

Raise the mower

If you insist on turf, set the mower high, and go around the exposed roots rather than over them. Every scalped root is a wound.

Roots in the wrong place

Roots heading for the driveway, the walk, the septic drain field or the foundation are a different conversation with different options, and we have covered each:

• Roots Lifting Your Driveway?
• Tree Roots and Your Foundation
• Tree Roots in Your Septic Tank and Drain Field

In every case the answer starts with an assessment of what cutting that root does to the tree, not with a saw.

When surface roots mean something else

Roots lifting on one side of a tree, with a crack in the soil or a mound forming, is not the same as roots surfacing gradually. That is a root plate starting to move, and it is a hazard. If the roots on one side seem to have come up recently, especially after a storm, call us. See My Tree Is Leaning.

Frequently asked questions

Can I grind the surface roots down flush?

Grinding the top off a live structural root is the same as cutting it, with a wider wound. It is done sometimes for a specific root in a walkway, but it is not a way to reclaim a lawn.

Will the roots damage my house?

Roots lifting a slab are a real possibility for a patio or walk. Roots damaging a properly built house foundation are much rarer than people think. We covered the difference in the foundation post above.

How much of the root zone can I mulch?

All of it, if you like. Out to the drip line is the ideal. Two to four inches deep, pulled back from the trunk.

Do surface roots mean the tree is unstable?

No. They mean the tree is mature and the topsoil is shallow. Roots that have lifted suddenly on one side are the concern.

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ArboristRX assesses root problems and advises on root zone care across Edgewater, New Smyrna Beach, Port Orange, Oak Hill and Volusia County. Call (386) 444-5959 before anyone cuts a root.