Why You Should Never Cover Your Tree Roots Above Ground, An Arborist Says

• Covering a tree’s roots above ground can limit the tree’s access to oxygen and moisture which helps them grow and stay healthy.
• Avoid cutting, trimming, or removing tree roots because it can make the tree woody and unstable, especially during storms.
• To discourage root growth at the surface level, try using mulch to cover the roots, loosen compacted soil, or hire a pro arborist.

Despite their seemingly breezy maintenance requirements, trees can be tricky to care for especially if not done properly—this also extends to their root systems. Is it better, for instance, to cover tree roots or leave them alone? To gather these answers and more, we reached out to an expert tree arborist to share their best insights.

Should You Cover Your Tree Roots Above Ground?

No, you should not cover the tree’s roots. according to Eric North, a certified arborist and urban forestry program manager at the Arbor Day Foundation.

“Oxygen and moisture are typically most available to tree roots in the open pore spaces of the upper soil, often in the upper 18 to 24 inches,” he explains.

So, the deeper you go, the more compact the soil gets, which means less space for the oxygen and moisture tree roots need. If you cover the tree’s roots, the tree will only work harder to reach closer to the soil’s surface to reach water and nutrients. All the more reason not to cover your tree’s roots.

“The exception to this is when soil erosion or any other disruption to the soil environment exposes fine roots that had been below the soil surface,” North explains.

In cases such as these, you can add some soil to cover any newly exposed roots.

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Don’t Cut Your Tree Roots

But above all, don’t trim your tree’s roots. Avoid trimming, cutting, or removing tree roots when the tree is young or old.

“As roots continue to age, they become woody and their primary role changes to providing energy storage and stability for the tree,” North says.

So, damaging even old roots can kill the tree’s roots, result in a reduction in the tree’s growth, or lead to unstable trees that will need to be straightened or else may fall down during storms.

What to Do Instead

It’s normal for roots to want to be near the soil’s surface. North explains how when roots grow near or at the soil surface, it’s typically because that’s where the most ideal conditions exist. However, there are several things you can still do to discourage root growth at the surface level. 

• Correct the soil conditions at the time of planting. Loosen compacted soil and add in some new organic matter (such as compost).
• Hire a certified professional arborist to improve compacted soils and encourage root growth below the soil surface. Professional arborists have tools that use pressurized air to blow away and loosen soil without minimal damage to existing roots.
• Cover the tree roots with mulch. This will help the soil retain moisture while remaining covered by the mulch.

Are Exposed Roots a Sign of Good or Poor Tree Health?

Trees have adapted to a wide range of conditions, and their roots spread out to help them find the most nutrients. Above-ground roots are not necessarily indicators of tree health, North says. However, they can be a reasonable indicator of soil conditions.

“Surface roots frequently form when soils are heavily compacted or there is a high-water table,” North says.

Both situations can impact your tree’s ability to gather water and nutrients.

Are Some Trees More Prone to Above Soil Roots?

Yes, some tree species are genetically prone to producing shallow roots, North says. This can include such species and varieties as Ficus, mountain spruces, and trees adapted to areas prone to flooding.

“In this latter case, the shallow roots nature is likely an evolutionary adaptation to manage limited resources,” he says.