- Author: By Penny Pawl, U. C. Master Gardener of Napa County
Spring is here and it's time to clean and refresh your worm bed. You can harvest that precious gold—the worm castings—and use it to feed your plants.
Years ago, I graduated to large compost bins for my worms. These bins need cleaning about every two years. If you are using a small container, you may need to clean it more often. I do add new bedding to the bins whenever the bedding gets about halfway down.
If you have a small worm bin, you need to harvest the vermicompost, get the worms out and then return the worms to the bedding. There are several ways to do this.
In the past, when I had a small bin, I would remove the whole pile to a temporary container. I would put the worms and their castings on a screen with a mesh large enough that the worms could move through. I would place the screen over moist new bedding. Then I would expose the whole thing to a light bulb or to sunshine. Since worms are light sensitive, they would wriggle away from the light and into the fresh bedding.
Another option is to use the plastic net sacks that onions and potatoes come in. Fill a sack with fresh, moistened bedding and put some of the worms' favorite foods inside. Then put the sack on top of the vermicompost and the worms will move into it, leaving the vermicompost behind for your use.
This method takes a little longer, but it's how I harvest my big bins. When the sack is full of worms, I dump it back onto the new bedding and the critters go back to work.
If you have big bins, you will have a bigger harvest and you need to prepare for it. Gather all the materials for the bedding: torn newsprint (no shiny coated paper), dried leaves, plain cardboard, straw, rice hulls, shredded paper. It feels good to put my old tax records in there.
When I have the bedding ready, I take the bin apart and set aside any uncomposted material. I put the composted material in a wheelbarrow so I can begin the process of separating worms and compost. I put the uncomposted matter back in the bin and then add the new materials. I don't try to mix them. Instead, I make a big “lasagna” of Iayered materials. As the worms eat their way through it, they do the mixing. Be sure to moisten all of the dry materials first, especially cardboard. When the bin is full, water it well. If the materials sink a bit, just add more.
I place a tarp over the castings in the wheelbarrow and put one or two of my sacks full of worms into the bedding. Every few days, I check the sacks and move the worms and contents to the new bin. Sometimes I add new worms at this point, purchased from a bait shop.
Once the worms have departed, I sift the compost to remove big items like sticks or peach pits. Then I put this sifted vermicompost into large pans in the sun to dry. When it's dry, I transfer it to a lidded storage container. (I use a garbage can.)
Scatter the castings around potted plants and in your beds, and your garden will thrive.
Workshop: U. C. Master Gardeners of Napa County will conduct a free workshop on “Worm Composting” on Saturday, March 19, from 9 a.m. to 11 a.m., at the University of California Cooperative Extension office, 1710 Soscol Avenue, Napa. Learn how to turn yard and kitchen scraps into rich compost to use as a soil amendment or garden mulch. Register here. No phone registration.
Master Gardeners are volunteers who help the University of California reach the gardening public with home gardening information. U. C. Master Gardeners of Napa County ( http://ucanr.edu/ucmgnapa/) are available to answer gardening questions in person or by phone, Monday, Wednesday and Friday, 9 a.m. to Noon, at the U. C. Cooperative Extension office, 1710 Soscol Avenue, Suite 4, Napa, 707-253-4143, or from outside City of Napa toll-free at 877-279-3065. Or e-mail your garden questions by following the guidelines on our web site. Click on Napa, then on Have Garden Questions? Find us on Facebook under UC Master Gardeners of Napa County.