Volcano Mulch Removal Project by the village hill community

Our friends at Village Hill noticed that most of the trees in their neighborhood had been volcano mulched over the years. With the leadership of Mindy Theroux and Bob Haxby, a group of volunteers were gathered and they set out on the arduous task of removing the mulch without damaging the trees. Over the course of several work days, they’ve managed to save many of these trees that were destined to a slow failure.

All About Volcano Mulching

“A mountain of mulch, piled high against a tree trunk will not kill the tree immediately – it results in slow death.” Martha Smith, University of Illinois: Mulch Volcanoes

Volcano Mulching is an improper mulching technique where mulch is piled thick and high against the trunk of a tree. Look for it next time you are shopping, it is most often seen in commercial and public landscapes. Mulch should never touch the trunk of a tree. The trunk is not meant to be covered, and doing so invites pest, disease and improper root structure. Here are the negative effects of improper mulching technique:

  • Deep mulch can lead to excess moisture in the root zone leading to root rot and insect and disease problems.
  • Thick layers of fine mulch can become matted and may prevent the penetration of water and air, and anaerobic “sour” mulch may give off odors.
  • Failure to develop a normal root flare which stabilizes the tree. These trees may be more likely to fall during a storm.
  • Girdling roots: mulch piled around the trunk promotes the growth of secondary roots, which can encircle the trunk and choke off the trees main roots

Here is a before and after picture of the volcano mulch removal, provided by Mindy Theroux:


Correct Mulching Techniques

Mulch is very important to a newly planted tree’s health and ability to thrive. According to the Arbor Day Foundation, the benefits of mulching include:

  • Mulch insulates the soil helping to provide a buffer from heat and cold temperatures.
  • Mulch retains water helping to keep the roots moist.
  • Mulch keeps weeds out to help prevent root competition.
  • Mulch prevents soil compaction.
  • Mulch reduces lawn mower damage.

To add mulch to your tree, remove any grass within a 3 to 10 foot area depending on the size of the tree. Spread mulch 2-4 inches deep, to the drip line of the tree if possible. Do not let the mulch touch the trunk.  The mulch should form a flat donut with the trunk in the center.   Alternatively, use the “3x3x3 rule” or 3 inches of mulch, 3 inches from the trunk, in a circle 3 feet wide.