Sometimes it’s tricky to tell what’s too much, not enough or just right for our trees.

Take mulching, for example. It’s a must for proper tree maintenance, but when mulch is too high and touches a tree’s trunk, it can cause problems.

Let’s look what can happen when you apply mulch that’s too thick around trees.

When is mulch around trees bad?

To be clear, mulch is great for trees (when it’s applied correctly). Mulch reduces weeds, conserves moisture and improves the soil, which helps your tree stay healthy!

But when it comes to mulch, it is possible to have too much of a good thing. Piling mulch too high and covering a tree's trunk, also known as “volcano mulching,” can cause decay.

Problems Caused by Mulch That’s Too Thick Around Trees

When mulch is too high and sits too close to a tree’s trunk, it causes two main issues that can slowly damage your tree over time.

  1. Problem: Too much mulch smothers the tree’s roots.
    Consequence: Roots might grow up through the mulch in search of air. That can cause them to “girdle” or wrap around the trunk, which chokes the tree by cutting off its water supply.

  2. Problem: Moisture builds up.
    Consequence: That excess moisture between the trunk and mulch volcano creates perfect conditions for wood decay diseases, like fungi. Plus, deteriorating bark at the tree’s base can lead to an unstable foundation.

Luckily, preventing these problems is as easy as mulching your tree the right way.

Click here for step-by-step instructions on how to best mulch your trees!

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