Yes, unfortunately, we have this problem in Fort Lauderdale and throughout South Florida. With all the moisture we have in the area, "Volcano mulched" trees are very susceptible to decay and the unwanted roots mentioned below. –Gene
By Paul Cappiello
Crestwood, KY (May 29, 2015) — Thanks to tree friend Paul Cappiello at Yew Dell Botanical Gardens for calling out the practice of "volcano mulching" and demanding an end to it. His article created a firestorm on social media this week. Find out what Cappiello has to say about the practice and why it's so bad for urban trees.
Photo Courtesy of Yew Dell Botanical Gardens
According to Cappiello, "Now to be clear right of the bat, let's get this out of the way. Volcano mulching is bad for trees.… Let us count the ways." And he does — four of them to be exact. Here they are:
Smothered Roots — Volcano mulching essentially plants a tree too deeply. Even if you plant at the right height, the mounds and mounds of mulch will act like additional soil volume, seriously limiting the tree's chance to flourish.
Unwanted Roots — What? Aren't all roots good for the tree? Not really. Volcano mulching tends to encourage the tree to produce roots out into the mulch pile rather than in the soil. The result is that later in the summer, when that loose mulch dries out, those roots will be the first to die off.
Fungus and Rodents … and Bears, oh my! — Deep piles of mulch around the trunk form the perfect place for decaying fungus to thrive. Crown rots, root rots, you name it … they are all encouraged by mulch volcanoes. The fluffy mounds are also the perfect place for mice, moles and voles to burrow. And guess what … all those little rodents love to snack on tree bark.
Think of your wallet — If you are doing the mulching yourself, you're buying mulch you don't need. You're hauling mulch you don't need. You're spreading mulch you don't need. If you're paying someone to do the work it's even worse. They're buying the mulch and marking up the price.
Cappiello concludes: "Bottom line … mulch is good … volcanoes are bad. Keep the mulch at 2" deep and remember, more of a good thing ain't always such a good habit." Read his full — and very lively — article, "Volcano mulching is a no-no," The Courier-Journal