Careful with the mulch

Published 8:21 pm Saturday, April 23, 2016

It’s been instilled in most of us that mulch is a good thing. We know that mulch applied around the base of our trees will reduce weeds, cool the soil and conserve moisture. Recommendations suggest that a two or three inch layer will do the job — so why wouldn’t more be better! Surely if three inches is good then six should be great.

Wrong, wrong, wrong! A new term — ‘mulch volcano’ — has been coined in the landscape industry.

When a thick layer of mulch is spread around the trunk of a tree several things can happen, and they are all bad.    The mulch will indeed hold moisture, but it will be around the tree trunk. The moisture creates conditions where the bark starts to decay, allowing fungi, bacteria and insects to get under the bark and cause problems internally for the tree.

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Circling roots are another problem commonly found in ‘mulch volcanoes.’ In this moist environment a tree will begin to grow roots into the mulch instead of outward into the surrounding soil.

To properly mulch your tree, first spread an even two to three inch layer around the base. The diameter is up to you, I personally like big mulch rings around trees to ease lawn mowing and reduce edging.

After the mulch is applied, use a rake or by hand pull the mulch back away from the trunk. As the mulch is pulled back, contour the mulch to resemble a bowl. This will help collect water and direct it towards the root system during irrigation or rain.

This is a great time to spruce up existing landscape beds with a fresh layer of mulch. Just keep in mind that trees don’t grow out of volcanoes.


Rebecca Bates is director of the Lincoln County Cooperative Extension Service. To contact her, call 601-835-3460.