Marc Welch, Newton’s Urban Tree Forester, is passing along a tip about how to mulch around the base of a tree trunk. Avoid mulch “volcanoes” where the piles of mulch surround and pile up against the bases of trees (and shrubs).

Proper application of mulch helps retain moisture and protect trees from mowers and string trimmers. But when mulch is piled too close and too high:

  • The tree bark is kept constantly moist, which leads to insect infestation, rodent damage, fungal growth, and cracks in the bark.
  • Tree roots do not get enough oxygen, eventually compromising tree stability.
  • “Adventitious” roots begin to grow above ground, instead of deep in the ground where they are meant to grow. Adventitious roots can turn into girdling roots which strangle the tree.

All this translates into a slow death for the tree.

To keep your trees healthy, remove mulch volcanoes by carefully raking mulch away from the trunk of the tree. Practice good mulching, by placing a ring (or “donut”) of mulch around the tree, with no mulch piled up against the trunk. Use just enough mulch to suppress weeds and contribute to the soil.

Annually our Urban Forestry staff members, using proper techniques, apply mulch around over 2,000 young city trees.

The above was originally published in Mayor Ruthanne Fuller’s newsletter.