I first learned vermicomposting––the practice of feeding kitchen scraps to worms––from Will Allen of the now-well-known Growing Power in Milwaukee, WI. Back then, I was a third grade teacher in the Milwaukee Public Schools taking a summer  course about science teaching. A few years ago, while waiting in line at The Cheeseboard in Berkeley, I saw Will Allen’s likeness on a poster for a food movement event. I now see Will Allen in person at national food and farming conferences. He is, in a way, a big part of how I got my start as a garden educator. Recently, I had the opportunity to share my early lessons with a dozen or so fellow garden educators in Napa.

Ask any kid who has been exposed to garden-based education where s/he thinks soil comes from and they’ll exclaim, “Worm poop!” Although there’s much more to it, worms do important work under the ground. Earthworms (Lumbricus terrestris) are especially important to aerating the soil with their tunneling. Although they are decomposers, earthworms are not the worms used in vermicomposting.

Because vermicomposting is best done in a closed system (i.e., an aerated container with moist bedding), it offers a model of decomposition that isolates a single decomposer, the red wiggler worm (Eisenia fetida). Like common earthworms, red wigglers are thought to be non-native to the US, but they have become relied upon extensively in home gardening and commercial enterprises alike. The main reason the red wiggler has gained so much notoriety is that it can eat half of it’s own body weight every day! This makes it a very efficient decomposer. Furthermore, the castings left behind are easy to harvest and use in the garden.

Building a worm bin is simple. Many organizations offer tips and suggestions (check out Cal Recycle’s comprehensive list) and you can even purchase a “worm condo” to make the process of harvesting castings even easier; however, I employ the same methods I learned from Will Allen nearly two decades ago: drill holes in a plastic bin, line it with cardboard and moist shredded newspaper, place your worms in their new home and feed them kitchen scraps. For more detail, see the UC Master Gardeners of Napa County’s Healthy Garden Tip: Nature’s Recyclers.

After I learned vermicomposting back in 2001, I gathered gallon-sized ice cream buckets from my grandpa’s basement and had kids construct “table top” vermicomposters. If ever there was a post-recess attention getter, this was it. Students would sneak fruit and vegetable scraps from their lunches to feed their “pet” worms every day. Composting indoors was especially useful in the urban landscape, where the school garden movement hadn’t yet sprouted. In addition, it can be done year-round, unlike backyard piles that freeze in the winter.

In schools, vermicomposting is a viable alternative to the more traditional compost pile for several reasons. Many administrators prohibit active compost piles in the garden due to the misconception that they smell or attract critters. I can attest to the presence of termites, cockroaches, and ants found in older school buildings and a compost pile that is ignored can potentially attract mice, skunks, or raccoons (although these are rarely seen during school hours and present far less danger than feral cats who sometimes use the garden for a litter box).

Another reason to vermicompost is that “hot” composting takes more effort than a dedicated classroom teacher has. Most of the educators I know who use the garden for instruction often do not have much extra time to nurture an active pile, which involves keeping a regular supply of “green” (nitrogen-rich) and “brown” (carbon-rich) waste, regular turning with a pitchfork, and seasonal sifting for use in the garden. Vermicomposting, on the other hand, is relatively effortless.

Arlene Bates, of the School Garden Task Force, drills holes in a worm bin.

Debbie Stevens, of Worm Endings Unlimited, demonstrates how to harvest worm castings.

Master Gardeners show educators how to assemble their bins.

Vermicomposting is so rewarding that a group of school garden educators in Napa eagerly signed up for a recent event jointly hosted by the County of Napa Recycling and Waste Reduction Division, the School Garden Task Force, Worm Endings Unlimited, and Pueblo Vista Magnet School. They learned to assemble a bin (and took one for their school site, complete with worms), harvest the castings and make worm “tea” a liquid dose of beneficial microbes for the garden. I was thrilled to share this practice with my colleagues as a tribute to Will Allen, my first vermicomposting teacher.