The benefits of mulch cannot be overstated. All types of mulch provide weed control benefits, which increase landscape plant health and growth by reducing competition for water and nutrients. All mulches also reduce soil erosion and runoff, as well as the impact of raindrops on the soil surface. Mulch is a very cost effective way to save on your landscape’s water, fertilizer and herbicide needs. Plus, a nicely mulched yard always looks neat, clean and inviting.
Mulch should be applied annually, as needed, in the spring or fall. This timing will maximize weed suppression and reduce erosion. A two to three inch thick layer of mulch is ideal – if the mulch is too shallow, benefits are negligible, while if the mulch is too thick, it may be difficult for water to penetrate it efficiently.
Mulch is available as organic (bark, compost, woodchips, well rotted manure, leaves, sawdust, etc) or inorganic (gravel, decomposed granite, river rock, etc). With all the different sizes, colors and types of mulch available, it’s easy to find an option that fits your landscape and appeals to your aesthetics and pocketbook.
Organic mulch improves soil composition by stimulating beneficial soil organisms. As it breaks down, organic mulch adds nutrients to the soil, which helps to feed your plants. Organic mulch also protects the soil and plant roots from temperature extremes. In the summer, this means reduced head absorption and in the winter, protection from freeze events.
A word of caution – some mulches, such as recycled tires, can dramatically increase soil temperatures or, as they break down, leach potentially damaging chemicals into the soil and others, such as recycled glass, can heavily reflect heat and light onto plants, which can cause stress to the landscape, so chose your mulch wisely.
Improving garden soils with organic matter. Oregon State University Extension publication, EM 8677. January, 2002.
OSU Extension Publications