Mulch has all sorts of wonderful benefits for your landscape. But if it’s too close, too thick or too coarse, it can also cause problems! Here are three rules for proper mulching etiquette.
Not Too Close. Mulch volcanoes, like the image at right, are not only an eyesore. They also endanger a tree’s health. When mulch is mounded up around a tree’s trunk, it keeps the tree’s bark consistently moist. These are ideal conditions for a host of insect and disease problems. The warm, humid environment inside a mulch volcano is also a good growing environment for tree roots, which can girdle and eventually kill the tree.
Proper mulching etiquette requires that mulch be applied evenly around the base of the tree or shrub. It should lie flat, and always be pulled back several inches away from the tree’s base.
Not Too Thick. Applying mulch around the base of your trees or shrubs is a good way to suppress weeds and help retain soil moisture. But if the mulch is applied too thickly, the mulch itself will absorb rainwater and overhead irrigation, and prevent that water from reaching the tree’s roots. An overly thick layer of mulch can be an inviting environment for insects and even small rodents that can nibble on the tree’s bark.
Measuring from the soil surface, your mulch should be no more than 3-5 inches thick. Before applying a fresh layer in the spring, remove some or all of the mulch from the previous year and add it to your compost pile.