Trees That Tear Up Asphalt

Unsuitable Trees

• Some trees have roots that grow horizontally, just under the soil surface. As the tree matures and the roots increase in diameter, they often become exposed above the soil. Roots that grow under asphalt will push against the pavement, causing cracking and lifting. Trees that cause asphalt damage include American elm, American sycamore, beeches, hackberries, live oak, London planetree, Norway maple, pin oak, red maple, river birch, silver maple, southern magnolia, sweetgum, weeping willow and willow oak.

Better Options

• Trees that grow deep roots are more suitable for planting near asphalt. Good choices for planting along roads and other paved surfaces include American hophornbeam, amur maple, arborvitae, Arizona cypress, chastetree, Chinese evergreen oak, Chinese juniper, Chinese photinia, Chinese pistache, cockspur hawthorn, crab apple, eastern red cedar, English oak, European hornbeam, Foster's holly, ginkgo, golden raintree, green ash, Japanese crape myrtle, lacebark elm, Rocky Mountain juniper and magnolia.

Planting Near Asphalt

• Consider installing root barriers at planting time. Vertical barriers that extend 18 to 24 inches deep divert the roots from the paved area and reduce the growth rate of the tree. Large trees provide effective shade, but their roots are more likely to become a problem. Plant large trees such as oaks up to 25 feet from the paved area. The soil around asphalt is usually compacted, making it difficult for trees to grow deep roots. Replacing the soil with a structural soil mix before planting gives the tree a loose, porous foundation in which to grow healthy roots. A structural soil mix, sometimes called an engineered soil, is a mixture of gravel and soil that prevents compaction.

Other Considerations

• Standing water can also damage asphalt. Avoid trees with large, dense canopies that provide dense shade and prevent water from evaporating quickly. You should also consider any maintenance problems the tree may create. Avoid trees that drop messy fruit and large leaves and pods. Near patios and other areas where appearance is important, trees that drop fruit and berries can leave stains that are difficult to clean.