Summer is upon us and if you haven’t already done so, now is a good time to apply an organic type of mulch around the trees, shrubs and other plant material in your yard.
Where to get mulch and free wood chips chips
Organic mulches can be purchased at garden centers. Sacramento Municipal Utility District offers free wood chips, which can be picked up at the SMUD Yard at 6100 Folsom Blvd. Hours are 9 a.m.–2:30 p.m. Monday–Friday; telephone 732–5854. Be sure to bring your own tools to load and bags to carry them or tarp to cover a pickup load.
Free wood chips are also available through a new app that helps arborists get rid of wood chips and gardeners get cheap mulch. It is getchipdrop.com.
Just what is mulch and why is it important? Mulch is any material such as straw, leaves, wood chips, plastic film, or compost spread on the soil surface to cover and protect it. Mulches such as plastic or rock over plastic are not recommended around trees or other plant material. Plastic mulches do not allow water to penetrate the soil and can also interfere with gas exchange below the soil that encourages root diseases.
Organic mulches can be effective in controlling annual weeds. They exclude light from weed seeds, which inhibits germination. The coarser the material, the deeper the mulch must be to prevent light from filtering down to the soil. Mulching is a beneficial treatment. It reduces surface evaporation and the soil stays moist longer which reduces water use. Soil erosion and water loss are reduced because the mulch breaks the impact of rain and sprinkler drops and slows down the movement of water. Organic mulch cools the soil temperature by as much as 10 degrees. Conversely, the use of rock over plastic will increase the soil temperature by 6 degrees.
Soil is a living organism made up of earthworms, soil microorganisms, bacteria, and fungi. Organic mulches are a benefit to these organisms, especially earthworms which feed on live and dead organic matter. Earthworm activity aerates and mixes the soil and is conducive to mineralization of nutrients and their uptake by trees and vegetation.
The application of mulch is one of the best things you can do for your trees, especially young trees. Grass growing around young trees can significantly reduce tree growth by as much as 65 percent. Keep the grass at least three feet from the base. Organic mulches benefit mycorrhizae, which is soil fungi that colonize the tree’s absorbing roots. The mycorrhizae help the tree with mineral absorption and play a protective role in keeping harmful pathogens away. When applying mulch, don’t pile it around the base of the trunk; keep it six inches away which will prevent diseases.
Mulch should be one to three inches deep for finer materials such as saw dust, grass clippings, or composted manure. It should be three to six inches deep for bark, wood chips, or straw. If you have a slope, shredded cedar is recommended because it knits together and doesn’t easily slough off or wash away. Laying down a weed barrier or landscape fabric before you apply mulch isn’t recommended because it’s a barrier for earthworms and soil microorganisms.
By Dan Pskowski Viewpoint staff writer