If you see big roots exposed, curling or snaking on the soil’s surface around a tree, it can be a sign of trouble.

Tree roots normally grow just below ground, in the top 12 to 18 inches of soil. They spread much wider than most people realize, but they don’t stay on the surface unless they’re forced to. Roots can be exposed by:    

  • Rain, runoff or wind may erode the soil around roots. This is especially common on slopes.
  • Lack of space. The tree may simply not have enough space for its roots, if it’s hemmed into a small area by sidewalks, streets, and buildings. When a growing root encounters an obstacle, such as a foundation or a curb, it may be deflected to the surface.
  • Where people trample a tree’s roots zone, they may wear away the soil or pack it down so far it exposes the roots.

When roots are above the soil, they’re easily damaged. They can be sliced by lawnmowers or string trimmers, or worn and torn by foot traffic. Damaged roots can’t do their job of collecting water and nutrients to support the tree.

Don’t try to rebury the roots by piling on more soil. The soil may end up too deep or tightly packed, so the fine feeder roots can’t absorb oxygen.

Do spread mulch over the roots. This will:

  • Cushion the roots
  • Insulate them
  • Discourage foot traffic
  • Keep lawnmowers away (there’s no need to mow mulch)

Do use an organic material such as wood chips or shredded wood. Spread it in an even layer 3 to 4 inches deep over the surface of the soil.

Do make the area of mulch as large as it needs to be to completely cover the exposed roots, even if that means covering an area of lawn. It’s healthier for a tree to be surrounded by mulch than by grass.

Don’t pile mulch against the bark of a tree; that can lead to rot or disease. Always spread it evenly. Be on alert. The mulch will decay over time. When it grows thin, you can add more mulch right over the old, as long as it never gets more than 3 to 4 inches deep.

Exposed roots aren’t just a dangerous tripping hazard; they can spell danger for the trees they support. Take steps to protect mature trees by protecting their roots with good cover and insulation and then stay clear so you don’t create problems by your well intentioned attention.

Photo courtesy of Bartlett Tree Experts.

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