May 1, 2015
Volcano Mulching
The Super Students from Dorene Tieche’s fourth grade class at Munhall School performed an original skit, Tree Trouble, at last week’s Arbor Day Celebration in St. Charles. The “tree,” center, suffered from mulch that was mounded too high against its bark. In the end, though, arborists rescued the tree from its plight
Don’t try this at home! The “volcano” mulch around the base of this sapling topped out at 14 inches, deep enough to create problems with disease and pest infestation, as well as premature death. Luckily, the remedy at this point is easy: Pull the mulch away from the trunk and spread it evenly around the tree at a depth of two to four inches.
Thinking about planting a tree this spring? Think you know what you’re doing?
Just to be sure, you might want to check with a local tree care specialist. Many fine companies operate right here in the TriCities. We are, however, also extremely fortunate to have a group of dedicated tree prodigies–the Super Students of Dorene Tieche’s fourth grade class at Munhall School in St. Charles.
Just over a week ago, on Friday April 24th, these talented individuals put on a series of performances at the City of St. Charles’ Arbor Day Celebration. Through song and dance, a Tree Trivia contest and a student-written, -casted and -directed play called Tree Trouble, the students educated the assembled crowd on the importance of planting trees properly.
I don’t know if you’ve noticed or not, but there are a lot of property owners around here who could use a refresher course in tree planting and maintenance. Trees throughout our region are suffering—though not for the reasons you may think. Their plight has nothing to do with emerald ash borers, Dutch elm disease, oak wilt or any other commonly discussed afflictions.
Nope, our trees are being hurt by our own good intentions.
Whether planting a brand new tree or tending to an old favorite, many people have the tendency to “treat” their tree to a heaping helping of mulch. Piled high and deep, as if more is better. If only these folks knew that, when it comes to mulch, you can definitely have too much of a good thing.
In recent years, the practice of “volcano mulching” has become all too common. You’ve probably seen it yourself, maybe even copied the look because you saw someone else doing it: Tossing shovelful after shovelful of moist, fragrant wood chips around the base of a tree until it looks like a miniature Vesuvius or Krakatoa, only with a trunk instead of lava sprouting out of the middle.
I can almost understand the allure. Mounding mulch can make you feel like you’re tucking the tree in for the season, providing a thick layer of protection from errant lawnmowers and weed whips. In fact, if you look at a mulch volcano just right, you may find it triggers memories of the blanket that was wrapped around the base of Charlie Brown’s Christmas tree. Not to mention Linus’s touching words: “Maybe it just needs a little love.”
However, if you really love your trees, the last thing you want to do is pile up the mulch. It’s not only wasteful, but also downright harmful to trees of all species. Pushed up against the bark, the mulch actually creates a micro-climate of moisture and warmth. Left unchecked, these conditions will cause rotting of the bark.
Once this vital, protective layer of the tree is compromised, insect pests, fungi and disease will follow. The stressed tree might also start sending out roots into this unnatural, above-ground environment. Unlike the strong roots of the soil, these small, weak growths only sap away more of the tree’s health.
The horror stories continue if the volcano isn’t corrected… Over time, wayward roots actually can encircle the tree and girdle it—that is, prevent nutrients and water from flowing up and down in the tissues just inside the bark. Thus deprived, the tree dies—literally killed by what was perceived as kindness.
So what’s the solution?
Like Mrs. Tieche’s fourth graders depicted in their play, mulch needs to be spread out beneath a tree, to a depth of 2 to 4 inches. Make sure the root flare–that expansion at the base of the tree, right where it meets the ground–is exposed. Rake the mulch so that it’s flat, not rounded, in order to allow water to soak in rather than run off.
As for how far out to spread the mulch, the City of St. Charles Public Works Department offers these guidelines: Mulch should be applied toward the trunk from the drip line (the space directly beneath the outer circumference of the tree branches). If this is not practical, minimum mulch circles should be 1.1 feet for small trees, 3.3 feet for medium trees and
9.9 feet for large trees.
When applied properly, wood mulch provides a good source of nutrients as well as protection for your trees. Because it reduces evaporation, mulch also can reduce the need for watering.
A little attention to detail this spring—a peak season for planting and mulching—can offer big dividends further down the road. The Super Students from Munhall will tell you, as they did during the happy ending of their Tree Trouble skit: “If you want to plant a tree, plant it right. And it will live for many years to come.”
Pam Erickson Otto is the manager of nature programs and interpretive services at the Hickory Knolls Discovery Center, a facility of the St. Charles Park District. She can be reached at 630-513-4346 or potto@stcparks.org.