Mulching Trees

Mulch is a material placed over the soil surface of the trees' root zone to maintain moisture and improve soil conditions. Mulching is one of the most beneficial things that can be done for the health and growth of a tree. A thin layer of mulch (2-4 inches deep) can improve soil structure, oxygen levels, temperature, and moisture availability.

Recommended Mulch Materials

Good quality mulch materials are usually readily available. Organic materials are preferable over inorganic materials (rock, stone, shredded rubber). When organic mulching materials decompose, they must be replenished.

  • Wood chips, composted for 4 months minimum
  • Pine needles
  • Tree bark
  • Leaf mold
  • Compost

When to Mulch

  • Annually, in spring, before soil moisture decreases and temperatures increase
  • Prior to, during, and after construction or infrastructure changes affecting tree roots and tree health
  • After tree injury

How to Mulch

  • Apply mulch in a circle covering the entire root system of a tree. Most of the fine, absorbing roots of a tree extend well beyond the tree canopy, or drip line.
  • Mulching with a deep layer can be harmful! The general recommended mulching depth is 2-4 inches.
  • Mulch piled high against the trunks of young trees may lead to insect and disease problems. Keep mulch at least 6 inches from the base of the tree trunk.

Benefits of Mulch

  • Conservation of soil moisture
  • Improvement of soil structure
  • Reduction in soil compaction
  • Increase in soil aeration
  • Increase in nutrient availability
  • Suppression of grasses and weeds
  • Aesthetically pleasing
  • Helps prevent damage from mowers and weed whackers