Spotlight Columns

Grow for it! Mulch magic

By Barbara Finley
UCCE Master Gardener of El Dorado County

Unless you are Punxatawney Phil and still in your underground hole, you have heard that California is in a drought. Precipitation this year has been minimal, and the water supply is anticipated to be limited. With such a water reality, does that mean you can’t garden? Of course not! It just means being smarter with resources — and using mulch.

Mulch is material put on top of the soil, and it can be beneficial to all places in your yard — flower and vegetable beds, around shrubs and trees, just about anywhere in the yard. Benefits of mulch include reducing water loss, suppressing weed growth and insulating the soil from temperature extremes.

There are two basic categories of mulch: organic and inorganic. Organic mulch was once a living material, such as chopped leaves; inorganic mulch consists of inert material such as gravel or black plastic. Since organic mulch was once alive, it decomposes over time and adds nutrients to the soil. The best choice is dependent on the needs and desired appearance in your garden.

When using mulch to suppress weeds, be sure the mulch itself is weed free. You do not want to encourage additional weed growth.  A layer must be laid thick enough to block sunlight, which weed seedlings need to grow.  Put down 2 to 3 inches of mulch in shady areas and 4 to 6 inches in sunny areas. Using mulch reduces the need to use chemical herbicides, which lessens the risk of water contamination.

As an additional benefit, mulch acts as an insulator, keeping subterranean plant roots cooler during hot days and warmer during the cool periods. During the long, hot days of summer, properly applied mulch can reduce soil temperature by as much as 10 degrees Fahrenheit, conserving soil moisture anywhere from 10 to 50 percent!

Organic mulch, such as shredded leaves and bark chips, add nutrients to the soil. With improved soil structure, better aeration, water percolation and soil nutrient movement occurs. Earthworms will appear and bring about more soil aeration and nutrient deposits in the form of their castings.

Mulch, such as wood chips or bark, can be purchased in bags or delivered by the truck load. Shredded leaves, grass clippings, straw and hay can also be used. When using mulch, match like with like, e.g., wood chips around woody trunks and leaves/grass in flower and vegetable beds. Keep mulch about 1 inch from stems and 6 to 12 inches from trunks to prevent rotting.

Black plastic can be used to warm up the soil temperature but be cautious, as it also prevents rainwater from getting to the soil. Put down soaker hoses first. Black plastic is not recommended near shrubs as the roots grow very close to the surface in search of air and moisture. Another concern is the black plastic is a petroleum product and there are few places it can be recycled. There are some biodegradable plastics on the market if that is the direction you prefer to go.

Mulch can contribute to your garden management in a variety of ways and its use, especially during times of drought, can be very beneficial.

Don’t miss the fifth annual Master Gardener spring plant sale on April 19 in the Veterans Memorial Building parking lot in Placerville. Many varieties of heirloom tomatoes and garden veggies will be featured, along with perennials, trees, shrubs and groundcovers that do well in our foothills climate. Plants that are considered water-wise will be prominently pointed out.

Master Gardeners are available to answer home gardening questions Tuesday through Friday, 9 a.m. to noon, by calling (530) 621-5512. Walk-ins are welcome at our office, located at 311 Fair Lane in Placerville. For more information about our public education classes and activities, go to our Master Gardener website at Sign up to receive our online notices and e-newsletter at You can also find us on Facebook.

Special to Village Life


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