One gardener posted to Reddit in a panic when they found a damaged tree in their yard.
“Dying trunk, volcano mound of mulch at base,” they explained, attaching photos of the problem. “How quickly do I have to mitigate this? … Need advice, thank you!”
Their photos showed a well-established tree with a huge vertical slash in the trunk. The interior looked weathered and dark, but the edges of the wound had grown up and out around it.
Despite the dramatic appearance of the damage, the growth was actually a good sign. “The wound is healing (occluding) nicely, actually,” a commenter said. “The mulch volcano needs fixing, though. Do it as soon as you can, shouldn’t take more than a few minutes.”
“Volcano mulching” is the practice of piling mulch against the trunk of a tree. It’s a common gardening mistake — after all, the tree needs nutrients from the mulch, doesn’t it?
But putting the material that close to the trunk doesn’t leave the roots room to breathe, and as they seek nutrients, they can grow in a tight ring that strangles the trunk, a problem called girdling. Experienced gardeners and landscapers on social media have spoken out against the practice.
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Sure enough, in this Redditor’s photos, there’s mulch piled up in a small mound right against the base of the tree, which could threaten the life of the tree if left as it is.
Another commenter gave advice about how to fix it. “The amount of mulch is great, but it needs to be spread out to about three inches deep, starting three to five inches from the base of the trunk,” they said. “Make sure the root flare is exposed.”
“It should be a donut over [the] roots, away from [the] trunk,” another Redditor added.
Thankfully, this story has a happy ending. The original poster added an update in the comments. “The volcano has since erupted! … or something…” they said. “Well, I dug away the mound and have exposed the root flare. Thank you for all the collective help!”
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