Volcano Mulch Kills Trees

I’ve lived in Middletown Township for nearly 40 years, in the same house in the same neighborhood. The lawn and tree services serving my neighbors seem to love piling up the mulch high on up trunk (they get paid by the cubic yard of mulch). And over the years I’ve witnessed many of these trees die—to the point where I can predict which trees will have to be cut down in the next few years.

Many homeowners are unaware of the dangers of piling mulch too high around the base of your trees, also known as creating "volcano mulch.” While mulching around trees can provide many benefits, such as helping to retain moisture, suppress weeds, and regulate soil temperature, it's important to be mindful of how you apply the mulch.

Piling mulch up against the base of a tree can actually do more harm than good. Here are a few reasons why you should avoid creating a volcano mulch effect:

1. Root rot: When mulch is piled too high around the base of a tree, it can trap moisture against the trunk, creating a humid environment that is conducive to the growth of fungi and bacteria. This can lead to root rot, which can ultimately kill the tree.

2. Pest infestations: Piling mulch up against the trunk of a tree creates a cozy hiding spot for pests such as rodents, insects, and even snakes. These pests can cause damage to the tree and may even spread diseases.

3. Girdling roots: If mulch is piled too high and too close to the base of a tree, it can encourage the growth of roots that circle around the trunk. Over time, these girdling roots can constrict the tree's vascular system, limiting the flow of nutrients and water and eventually leading to the tree's decline.

4. Bark decay: When mulch is piled up against the trunk of a tree, it can hold moisture against the bark, creating the perfect conditions for fungal growth. This can result in decay of the bark, weakening the tree and making it susceptible to diseases and pests.

5. Fire hazard: In dry conditions, a thick layer of mulch piled up around a tree trunk can become a fire hazard. Mulch is highly flammable, and if a fire were to start, it could quickly spread to the tree and cause extensive damage.

What is the proper way to mulch around trees? Experts recommend creating a mulch ring around the base of the tree, leaving a gap of a few inches between the mulch and the trunk. The mulch ring should be no more than 2-4 inches deep and extend out to the tree's drip line, which is the outer edge of the tree's canopy.

While mulching around trees is good, it's important to not over do it. Volcano mulch is not only a waste of resources and money, it can lead to issues that harm the tree's health and ultimately kill. Follow the proper mulching guidelines to ensure the health and longevity of your trees.