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Volcano Mulching: the Wrong Way to Mulch

Proper Mulching Techniques in Place of Volcano Mulching


When you see mulch piled high against the trunk of a tree, you’re looking at volcano mulching. And you never want to see volcano mulching. While there are many benefits of mulching for your trees, too much mulch or improperly-applied mulch can do more harm than good.


Say no to volcano mulching. The proper way to add mulch to a tree.
The correct way to add mulch around a tree. Say no to volcano mulching.

Well, What Does Mulch Do?

Mulch helps to keep the grass from growing next to the tree, holds moisture in the ground, and reduces the amount of annoying weeds from popping up. If you can extend mulch to the drip line of the tree, which is the outermost circumference of your tree’s canopy (from which water drips to the ground), mulch also helps your tree’s root system absorb moisture.


And What Does Volcano Mulching Do?

When mulch is piled up next to the trunk or flare of the tree, it creates excessive moisture, which can lead to fungal growth, decay of healthy tissue, and tree diseases. Not to mention, the mulch provides a place for insects to harbor.

All of these negative effects of volcano mulching can lead to stunted growth and loss of structural integrity in your tree. The tree should not look like a telephone pole springing from the ground. Root flares should be visible. Mulch should not cover the tree’s root zones and should not come into contact with the trunk of a tree.


Volcano mulching. Why do landscape installers do this?
Volcano mulching. The wrong way to add mulch to trees.

Oops! I Volcano-Mulched! Now what?

If you or your landscaper already piled mulch next to your tree, pull the mulch away from the tree in order that it’s not touching the flare, stem, or trunk. You’re trying to mimic the tree’s native habitat, creating a natural setting. If you walked in a forest, you wouldn’t see mulch or turf-grass piled up against the stem of a tree. By removing the excess mulch from the trunk, stem, or flare of the tree, you minimize the risk of disease and insect infestation.

Not only do you want to keep the mulch away from the stem or flare of the tree, but you also want to extend the mulch as far to the drip line as possible. Your tree’s feeder roots extend out to the drip line, and the mulch helps their absorption. In addition to the benefits of extending the mulch to the drip line, you reduce the chance of string trimmer or mower damage with a wide circle of mulch around your tree.


Can I Reverse Years of Volcano Mulching?

First, start by removing the excess mulch, you can then remove adventitious, girdling, and other problem roots that were hiding beneath the volcano mulch. After you finish excavating the old mulch, you can apply a thin and wide layer of mulch around your tree, preferably out to the drip line, while leaving the tree trunk, flare, and stem free of mulch.

If you are uncertain of how to do this, call a landscape professional who can help you get started on getting your tree back to a health state. Proper mulching is beneficial to your property and to your budget. Do yourself and your trees a favor by banning volcano mulching on your property.


Contact us if you need assistance evaluating your landscape.

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