Mulching
Mulch Volcanoes: The Common Landscaping Mistake That Can Slowly Kill Your Trees
Walk through almost any neighborhood in northern Illinois and you'll see them everywhere - trees surrounded by tall mounds of mulch piled against the trunk.
These are known as "mulch volcanoes," and despite their popularity, they are one of the most common - and most preventable - causes of long-term tree decline.
At Axis Tree Care Company, we routinely encounter healthy trees that are being slowly damaged by improper mulching.
What Is a Mulch Volcano?
A mulch volcano is exactly what it sounds like: a cone or mound of mulch piled high around the base of a tree, often covering the trunk and root flare.
Many people believe this protects the tree or helps retain moisture. While mulch is beneficial when applied correctly, piling it against the trunk can create serious problems.
Why Are Mulch Volcanoes Harmful?
Trees are designed to have their root flare - the point where the trunk widens into the major roots - exposed to the air.
When mulch is piled against the trunk, it creates an environment the tree was never designed for.
Over time, this can lead to:
- Bark decay from excessive moisture
- Increased risk of fungal diseases
- Stem-girdling roots that slowly choke the tree
- Insect and rodent damage hidden beneath the mulch
- Reduced oxygen around the base of the tree
- Long-term decline that may not become apparent for years
Many homeowners don't realize there is a problem until the tree begins thinning, developing dead branches, or showing signs of stress.
The Right Way to Mulch
Fortunately, the solution is simple.
Think of mulch as a doughnut - not a volcano.
Proper mulching means:
- Applying mulch 2-3 inches deep
- Keeping mulch 3-6 inches away from the trunk
- Spreading mulch outward over the root zone rather than upward against the tree
- Leaving the root flare visible
A wide, shallow mulch ring provides all the benefits of mulch while allowing the trunk to remain dry and healthy.
Why Mulch Matters
When applied correctly, mulch offers many benefits:
- Conserves soil moisture
- Moderates soil temperature
- Reduces competition from grass and weeds
- Adds organic matter as it decomposes
- Protects roots from mower and string trimmer damage
The goal isn't to use less mulch - it's to use it correctly.
Can a Mulch Volcano Be Fixed?
In many cases, yes.
If a tree has been buried under years of excess mulch, an arborist can often remove the accumulated material, expose the root flare, and inspect for problems such as stem-girdling roots or trunk decay.
Correcting the issue early can improve a tree's health and may help prevent more serious problems in the future.
A Simple Test
Take a walk outside and look at the base of your trees.
Can you clearly see where the trunk begins to flare outward into the roots?
If the trunk disappears straight into a mound of mulch, your tree may benefit from a closer inspection.
We're Here to Help
At Axis Tree Care Company, we believe that good tree care begins with proper planting and maintenance practices. Sometimes, a simple correction today can add years - or even decades - to the life of a valuable landscape tree.
If you're unsure whether your trees are mulched correctly or have concerns about their health, we'd be happy to provide a professional assessment and recommendations tailored to your property.