It’s spring! Time to get to work on your garden, your yard and your trees. A common, costly mistake you can avoid this spring is how you apply mulch to your trees. The more, the better, right? Your neighbor piles up the mulch on their trees, businesses with professional landscapers do the same, so that’s what you should do, right?
Mulch in contact with the tree’s trunk can cause it all kinds of problems. It can cause trunk rot, fungus and promote other diseases because it traps moisture against the tree and keeps it moist much longer than it normally would after a rain. Also, over time, trees may grow roots within a tall cone of mulch that can encircle the tree and eventually choke it to death. Those are called girdling roots and are a frequent result of too much mulch. In nature you’ll never find a tree with dirt or even leaves piled high on the trunk, so don’t do it in your yard.
What about deep mulch, away from the trunk? Is that bad? Thicker layers of mulch can help fight weeds and some mulch can help keep moisture in the ground, but too much can prevent air and water, especially from a light rain, from getting to the soil where the roots are. A thin layer of mulch, perhaps 2” thick or less total (new plus old mulch) is better for the tree. Perhaps the best role of mulch is to keep mowers and weed whippers from damaging the trunk and compacting the soil around a tree.
So, when you’re working on your own yard, be careful of the mulch. Too much of a good thing, like mulch, may damage the very thing you’re trying to care for.