Visiting Southern Missouri one summer day, I saw this. What is it? Doesn't it just remind you of a smokestack emerging from a volcano? Start looking around where you live; start looking for the picture above.
Fact is, you don't have to be in Missouri to see volcano mulching, or wood mulch piled around a tree. This type of malpractice is everywhere, and with all the new construction and fresh landscaping going in around Spokane, Coeur d'Alene, and Post Falls, I'm seeing it more than ever. You have probably heard that wood mulch around trees is a good thing, right?
Wood mulch can be both a good thing and a bad thing. It depends. It's like ice cream. Enjoying a little dish of ice cream is great and almost medicinal, but too much ice cream; there are consequences. A little mulch is great for trees, so a lot of mulch must be better?
What happens when you volcano mulch?
So what are the consequences of too much wood mulch piled up around a tree like a volcano? It's bad, because too much mulch traps excessive moisture and heat against the tree trunk. A trunk does not like to be wet and smothered. Piling up mulch (that is, volcano mulching) encourages rot, disease, pest problems, rodents, and suffocation.
🌋 Believe it or not, trees breathe, and volcano mulching is like a Wonder Bread bag over your face. You can sort of breathe, but you can't.
The right kind of mulch
Mulch for trees is made from shredded or chipped wood. There are many types of wood mulch; use tree leaves if you have to, but please never use grass for mulch. When wood mulching is done right, it helps retain soil moisture, suppress weeds, moderate temperature extremes, and promote a healthy, attractive landscape.
Why mulch matters: the science
This part is a little techy, but stay with me. When wood mulch breaks down, it replenishes the soil with fresh carbon under the tree. Carbon is life; all living things are made up of carbon. Microbes (the microorganisms that live in the soil) love to eat chips; not potato chips, wood chips. Microbial mineralization (decomposition) is a process in which soil microbes break down wood and mine the carbon to build healthy soil. This is great for your tree.
Give your tree a donut, not a volcano
You know what is really good for your tree? A donut. A three inch thick, flat pancake donut loaded with shredded bark mulch. If you can, maintain a mulch donut ring out to the drip line of your tree. The drip line is the imaginary circle on the ground where water drips from the canopy leaves.
Oh yeah, please don't forget the donut hole; the open space in the middle that keeps the tree trunk flare uncovered, unsmothered, breathing, and dry.
Bottom line
If you're planting new trees around a fresh build in Coeur d'Alene, Post Falls, or the greater Spokane area, getting the mulch right from day one saves you expensive problems down the road. If you've already spotted a volcano or two in your own yard, it's not too late to fix it.
Harris, R.W., J.R. Clark and N.P. Matheny. 1999. Arboriculture: Integrated Management of Landscape Trees, Shrubs, and Vines, 3rd Ed. Prentice Hall, Upper Saddle River, NJ (Mulch on Chapter 7, pp. 202-215).
2 Comments
The donut vs. volcano thing is going to stick with me. I walked out to my own yard after reading this and sure enough, one of mine is halfway to erupting. Pulling it back this weekend.
Keep pulling the mulch back until you can see the base of the trunk spread out into roots, like a chicken’s foot with the toes going out in different directions. If the trunk still looks like a straight pipe going into the ground, keep going. Easy fix, you got this.