In three short decades, volcano mulch has become one of the greatest threats to newly planted and young trees and shrubs. If unchecked, the significant monetary and human investment in greenscapes will result in more and more dead and dying trees.
Volcano mulch is the over-mulching of plant material, notably trees and shrubs. Mulch plays an important role in protecting plant material from irreversible lawnmower and weed whacker damage as well as providing for some control over weed competition and soil water retention. Seemingly, rings of mulch have also become landscape design features.
While deadly, the problem is simple; people are placing heaps and heaps of mulch around trees and shrubs and right next to the thin, vulnerable bark. The fact is you do not need more than 2-3 inches of mulch in depth for the desired purposes. Mulch should not come closer than 2-3 inches from the plant. Yet people are piling mulch 6 inches or more, and right on the trunks of the trees, causing damage to life sustaining cambium (the live tissue just below the bark). Beware of volcano mulch in your yard.
Article by Robert Ricard, Ph.D.