Volcano mulching sounds a lot cooler than it is. Volcano mulching is when you make a big pile of mulch along a tree’s trunk, as in the picture below.
The reason we’re looking at volcano mulching is that everyone says it’s bad, but no-one has really proven that it’s bad. The reasons that volcano mulching are supposed to be bad are twofold: First, the mulch could cause rot on the tree’s stem and second, because it might be possible for a tree’s roots to grow up into the mulch, potentially surrounding the stem, which might lead to the roots choking the stem as the
tree grows larger. Not a good situation.