Surface Roots in Lawns

Source(s): Randy Drinkard

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Much to the dismay of homeowners, trees sometimes develop roots on the soil’s surface. Surface roots can even buckle sidewalks and driveways. Shallow roots growing in lawns not only create unsightly lumps but they may also cause hazardous mowing conditions.

Although trees do send some roots down deep for moisture and stability, most tree roots tend to grow much more shallowly than most people think – usually only 8 to 12 inches deep. Just as the trunk of the tree grows in girth with age, so do the roots. So over time, some of the shallow, older roots of the tree will naturally enlarge to the surface. Sometimes, roots become visible due to erosion of the surface soil.

Once the roots appear on the surface, there is little that can be done to remedy the situation, without substantially damaging the tree. You can prune off the visible roots, but the damage to the cut roots and the fine feeder roots surrounding the area can harm or even kill the tree. Pruning the roots should be confined to situations where the roots are breaking up sidewalks or driveways.

Some homeowners have tried a temporary solution by applying a shallow, 1-inch layer of good-quality soil mix and then replanting the grass. However, it isn’t long before roots will reappear as they continue to grow in girth. A better solution would be to replant the affected surface area with a type of ground-cover plant that will not need mowing.

The best remedy for surface roots is to choose the proper plants for the situation. But if you already have a large, old tree with surface roots that you don’t want to lose, you may just have to learn to accept its intrusion into the lawn.

Other factors may cause roots to develop near the soil’s surface:

1. Compacted or heavy clay soils. Tight, heavy soils contain very little oxygen; therefore, root growth is restricted largely to the soil’s surface where oxygen is present. To reduce compaction, loosen the soil around the tree’s roots, if possible. If trees are growing in lawns, aerate these areas to relieve soil compaction and increase soil oxygen levels.
2. Waterlogged soils. Waterlogged soils have very little oxygen available for proper root growth and development. The oxygen that is available is located near the soil’s surface; thus, roots often develop at or near the surface. If soils become waterlogged, reduce watering and improve the drainage; avoid planting young trees in overly-wet locations.
3. Light or shallow irrigation. Plants growing in or near lawns that are not deeply watered often develop shallow roots near the soils’s surface. Apply enough water to throughly wet the soil to a depth of six to eight inches. In the absence of plentiful rainfall, applying one inch of water weekly to lawns should supply ample moisture to the proper depth.
4. Natural growth tendency. Some trees and shrubs just naturally develop shallow roots near the soil’s surface. Examples of plants that develop shallow root systems include; alders, elms, figs, honeylocusts, mulberrys, poplars, maples, sycamores and willows. Do not plant these or other shallow- rooted trees in or near lawn areas.

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Center Publication Number: 221