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Mulch Do’s and Don’ts

KANSAS CITY, Mo. – Mulching is a time-honored spring chore that keeps unwanted weeds from taking away from the beauty of flowers, trees and shrubs.

Mulch cools the soil, saves moisture, controls weeds and provides a unifying effect in the landscape, says University of Missouri Extension horticulturist Tamra Reall. Mulch also reduces damage from lawn mowers and trimmers, as well as reducing soil compaction.

But applying too much mulch or applying it incorrectly can damage plants and trees, Reall says. A few guidelines can make plants grow better and protect your home.

Choose the color and texture of your mulch to highlight the plant, not the other way around, she says. Use the same color throughout the landscape for best results. Think monochromatic and natural for a look that allows the eye to travel from one area of the yard to the next.

A variety of materials —from commercial wood mulch to cornstalks and even composted lawn clippings—can serve as mulch. Keep in mind that inorganic mulch such as pulverized rubber does not supply nutrients or improve soil structure. Organic mulch releases some nutrients as it decomposes, but the fertilizer value is small. Add fertilizer to the soil before mulching as needed.

Pile mulch about 3-4 inches deep in a ring a few inches from the tree trunk or plant. Spreading mulch too close to trees and shrubs can damage or kill them. Design so that mulch is higher on the outer edge. Placing mulch too close to the root flare and trunk of a tree or plant can cause root girdling, disease and decay, and provide hiding places for insects and small animals.

While good for plants, moisture in the soil is also good for some insects. One of the worst risks is termites, Reall says. Keep wood mulch a few inches from your home’s foundation. When applying mulch, leave a thinner-than-normal layer near the foundation so at least 6 inches of concrete is exposed. This allows termite tunnels to be spotted, she says. Termite mud tunnels are about the width of a pencil.

And while you’re working in the yard, get rid of standing water from places such as buckets and tires. “It is to everyone’s advantage to remove standing water in their yard where mosquitoes can lay eggs,” she says. “It only takes a tiny amount of water for a mosquito egg to grow into an adult.”

For more information, the MU Extension publication “Mulches” (G6960) is available for free download at