Don't let mulch volcanoes ruin trees

Updated Aug 25, 2022
landscaper adding mulch around plants in a flower bed
Kingstowne Lawn & Landscape

You don't have to live in Hawaii to see your clients' landscapes ruined by volcanoes. If your crews are using improper mulching techniques and creating "mulch volcanoes," they could ultimately be harming your clients' trees.

If you're not familiar with the term, a mulch volcano is when a tree ring is mulched with a big mound. Mulch is piled against the trunk of the tree. We see these all of the time and we know that it has become common practice, even though it's wrong. The more often these are seen, the more accepted they become. That's why it's important that you are teaching crews the proper way to mulch.

But first, let's talk about a few reasons why mulch volcanoes are so bad.

The problems with mulch volcanoes

The problem is mulch volcanoes is the mulch that is touching the tree's trunk. This can encourage disease and decay because the tree trunk never gets a chance to dry out. This moist environment is not healthy for the tree and can lead to insect problems, fungal growth, and cracks in the bark.

Piling up mulch can also deprive the tree roots of oxygen. And if the soil remains too wet and soggy, the roots can begin to rot.

Oftentimes trees respond to these conditions by growing new roots into the mulch (instead of deep into the ground as they should). As the mulch degrades, the roots can become exposed, which is also problematic. 

Over time, all of these problems can lead to the tree's decline and possibly even death.

How to mulch properly

The proper way to mulch is actually to create a mulch ring that resembles a donut. The tree should be at the center with no mulch piled up against it.

Another bad mulching habit is over-mulching. Mulch rings are very beneficial, but there is such a thing as too much! Over-mulching can lead to water build-up and the mulch can become soggy and saturated. If too much water is being absorbed by the thick layer of mulch, it's not reaching the tree's roots where it is needed.

Of course, you don't want to under-mulch, either. Aggressive weeds can break through a thin layer of mulch. 

Talk to crews about proper mulching

All of these reasons are why it's important to talk to your crews about proper mulching, even if they've worked in the industry before. The sheer number of mulch volcanoes that we see around our area tells us that plenty of landscaping companies are not practicing proper mulching habits. Because this improper practice has become so common, it gets repeated.

But you can break the bad mulching cycle by teaching crews to mulch the right way. It just may start saving trees in your area.

Krisjan Berzins next to his bio that reads, 'Krisjan Berzins is the president and CEO of Kinstowne Lawn & Landscape based in Alexandria, Virginia.'

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