Should I Mulch Around Trees?

Mulch around trees 3Applying mulch around trees is one of the best things you can do for the health of your trees. Especially for young trees, mulching is a quick and cost-effective technique that provides numerous benefits.

Benefits of Mulch Around Trees:

  • Almost doubles the growth rate of newly planted trees. Walnut trees experience an 89% increased growth rate while other hardwoods (oak, maple, hickory, birch, beech, and cherry trees) experience an increased growth rate of 79%.
  • Insulates the soil helping to provide a buffer from heat and cold temperatures.
  • Retains water helping to keep the roots moist.
  • Keeps out weeds to help prevent root competition.
  • Prevents soil compaction.
  • Helps tree’s soil accumulate and keep more nutrients
  • Reduces lawn mower damage.

Can You Apply Too Much Mulch?mulch around trees 1

Yes, it is very common for homeowners and landscapers to apply too much mulch. The most common example of this is when trees have mulch volcanoes. A mulch volcano is an industry nickname for piling mulch around a tree trunk forming what looks like a mulch hill. This can severely hurt the tree. When you use too much mulch you expose your tree to the following situations.

  • An increased susceptibility to insects & diseases caused by mulch irritation on the trunk of the tree.
  • Girdling Root Systems – a condition where smaller roots wrap around a dominate root choking it and not allowing the tree to absorb nutrients.
  • Rodent issues – mulch piled high against the trunks of trees create habitats for rodents that chew the tree’s bark.
  • Root Rot from excess moisture

Can Mulch Kill A Tree?

Yes, when trees suffer year after year from mulch volcanoes they start to experience the complications discussed above.  Once your tree has developed one or more these complications (root rot, a girdling root system, a disease, or an infestation) it can die.

What Can I Do If My Tree Has Been Over-Mulched?

If this is the first year your tree has been over-mulched simply go out and remove or spread out the excess mulch. Use the proper mulching tips in the next section below to make sure you redistribute your mulch correctly.

IMulch Around Trees 2f your tree has been over-mulched for years you will most likely need a few treatments to get it healthy again.

  • Root Collar Excavation: this process opens up the tree’s root zone using pressurized air. This doesn’t hurt the tree’s roots and allows the arborist to inspect the root system to see if there are girdling roots or root rot.
  • Treatments: based on what is found during the root collar excavation your tree may need treatment for root rot or root pruning to trim back the girdling roots.
  • Bio-stimulants: since your tree has been kept in an unhealthy situation for years bio-stimulants can be used as a multi-vitamin to make sure the tree has all the nutrients it needs to strengthen its immune system and recover from over-mulching.

Take a look at the video below to see use correct an over-mulching situation at a local HOA using a root collar excavation, root pruning, and proper re-mulching.


How Do You Put Mulch Around Trees?mulch around trees

Size: The best mulching goes out as far as the drip line of the tree. However, this isn’t reasonable for most homeowners with large trees. If mulching out to the dripline isn’t practical, apply mulch in a 2 to 3-foot radius around the tree instead.
Depth: About 2-4 inches

  • Do not pile the mulch against the trunk of the tree. Instead keep the mulch away from the trunk, so that the root flare zone is visible.
  • To refresh the look of mulch, lightly rake the top layers of the mulch, or simply remove the old mulch and replace with new mulch. Don’t pile new mulch on top of old mulch.
  • Do not use fresh wood chips for mulching around young trees. Fresh wood chips have a higher acidity and can injury a young tree.

Learn what not to do when you mulch around trees with our 5 Common Mulching Mistakes article.