Mulch: It's Got You Covered
by Anne Sutherland
Hot, dry summers also mean wildfire risk. If the soil underneath is properly irrigated, composted wood chips tend to smolder rather than flame up. Shredded rubber, pine needles, shredded cedar bark and eucalyptus are particularly flammable. Use only non-flammable mulch 0’-5’, low-flammability mulch 5’-30’, and large wood chips 30’-100’ away from structures. It’s OK to use composted wood chips in modest batches but keep them at least 30’ away from structures.
Mulch reduces the impact of raindrops on soil, thereby reducing erosion and improving water percolation into the soil.
Mulch also reduces the number of weeds and makes the few that get through easy to pull up.
Mulch helps suppress soil-borne diseases and makes a nice home for beneficial organisms, like earthworms digging dead surface material into the body of the soil. Some types of organic mulches, such as cedar chips, can help to repel certain types of pests, such as termites and ants.
Wood chips about 1” in length work well for landscape plants and are less likely to blow away than shredded bark. Gravel and rock are good for weed control and most succulents but provide no soil or microbe nourishment and can heat up the soil. Mulches that break down quickly, such as rice straw, grass clippings, or shredded leaves, are best used for vegetable gardens. Make sure these garden mulches are not matted down so the soil can get air and water. Finally, do not count on mulch preventing frost damage. You still need to protect frost-sensitive plants such as citrus.
Overall, using organic mulches is an excellent way to improve the health of your plants and soil, and using organic mulches is a sustainable choice that supports the health of the environment.
References and Resources:
Mulches for landscape plants: https://anrcatalog.ucanr.edu/pdf/8672.pdf
Mulches for vegetable gardens: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=24048
Mulch and fire in California: Mulch - Fire in California
Short video by Missy Gable on the Importance of Mulch