Mulch materials can help your garden grow
Mulch materials can help your garden grow
By Penny Pawl
NAPA VALLEY, Calif. — The Merriam-Webster dictionary defines mulch as “a protective covering (as of sawdust, compost or paper) spread or left on the ground to reduce evaporation, maintain even soil temperature, prevent erosion, control weeds, enrich the soil or keep fruit (such as strawberries) clean.
As master gardeners we are trained to rely on science-based research and to provide science-backed information. No folk tales. From that perspective, mulch is the answer. We are also taught that we don’t know everything about gardening, but we know how to look up the answers to our questions.
I am fortunate that a local tree service drops truckloads of mulch on my property on occasion that I share with others and use myself. Neighbors on my road also allow a tree service to dump chipped material at their home.
I mulch my soil to make it more hospitable for plant growth and easier for rain or irrigation water to penetrate. Compost applied as mulch will gradually break down, and bacteria and worms in the soil will work it in deeper. Like many other master gardeners, I use a process called lasagna composting — so named because it involves making layers of organic materials that will gradually decompose. I lay down damp, clean cardboard and put compost or small wood chips on top.
I use this method annually in my vegetable beds. If the cardboard hasn’t fully decomposed after a winter of rain, I cut holes in it and plant my veggies in the holes. If it does not rain much over the winter, I water the garden beds occasionally to encourage decomposition. Lasagna composting also works well in walkways for weed control. I have found the weeds that do come up are much easier to pull.
Mulch inhibits weeds, helps the soil absorb and retain water, regulates soil temperature and prevents erosion. Nature does its own mulching under large trees if fallen leaves are left to decompose. When mulching around trees, keep the material away from the trunk. Otherwise the moisture retained by the mulch can kill your tree. Also, don’t let mulch pile up against your home as very dry wood mulch can ignite.
Some people use rocks and stones as mulch, but this is not a great idea. Sunlight heats the rocks and can cause soil moisture to evaporate. Also, weeds love to plant their seeds in rocks, and then it can be difficult to uproot them
You can make your own mulch by having a working compost pile. Do not add weeds to the pile if they have started to form seeds. The weed seeds will not break down in the compost and will produce an abundant crop of unwanted seedlings. I don’t even put cantaloupe seeds in my compost pile for the same reason. Those seeds will sprout anywhere and everywhere I spread the compost. Even a rose bush can be a weed if it’s growing in a wheat field.
The city and county of Napa collaborate with local master gardeners to present compost workshops for interested residents. There are several ways to make compost, and I have done most of them except for hot composting, which involves mixing different materials such as manure, clippings and food scraps. If you don’t want to make your own compost, Napa Recycling & Waste Services will deliver compost to you.
The next master gardener compost workshop is scheduled for Saturday, Sept. 16. Save the date and watch for a registration announcement in this column. Come learn the whys and howof composting, including worm composting of your kitchen waste.
Food-growing forum: Join UC Master Gardeners of Napa County for a forum on “Beverages From Your Garden” on Sunday, July 9, from 3 to 5 p.m. at the University of California Cooperative Extension office, 1710 Soscol Ave., Napa. Register here.
Library talk: Join UC Master Gardeners of Napa County for a talk on “Resilient Landscaping for Drought and Fire” on Tuesday, July 11, from 4:30 to 5:30 p.m. at St. Helena Library, 1492 Library Lane, St. Helena. Register here.
Guided tree walk: Join UC Master Gardeners for a free guided tree walk on Friday, July 14, from 10 a.m. to noon at Fuller Park, Oak and Jefferson streets, Napa. Space is limited to 15, and each person must register separately. Register here.
Gardening with the masters: Join UC Master Gardeners for an educational gardening experience on Saturday, July 15, from 10 a.m. to noon, at OLE Health South Campus, 300 Hartle Court, Napa. Children ages 5 and older are welcome if accompanied by an adult. Class size is limited. Register at: Register here.
Help desk: The Master Gardener Help Desk is available to answer your garden questions on Mondays and Fridays from 10 a.m. until 1 p.m. at the University of California Cooperative Extension Office, 1710 Soscol Ave., Suite 4, Napa. Or send your questions to mastergardeners@countyofnapa.org. Include your name, address, phone number and a brief description of the problem. For best results, attach a photo of the plant. You may also leave a voicemail message with the same information at 707-253-4143.
Penny Pawl is a UC Master Gardener of Napa County.