Master gardener Heidi Stewart cautions that it's not for the squeamish.
There is a certain revulsion that must be considered and overcome if you plan to set hundreds of writhing worms loose on your rotting garbage. But for many serious gardeners, it's well worth the rewards of producing some of the best compost they've ever worked with.
"This is very rich," she says, fearlessly reaching into a plastic bin squirming with worms at work and pulls out a handful of dark soil. "All these microorganisms are going through the worm's systems. Their presence in the castings makes them much more accessible for the plants to take up in their roots. This matter is 11 times as rich as regular soil."
Stewart, who lives in rural Sebastopol, has maybe half a dozen small, covered worm bins producing compost just a few steps from her raised beds. The production is small. But all it takes is a cup of worm-enriched compost placed in a planting hole to create a happy plant.
"There is no more valuable soil. The people that know about it can't get enough of it," said Mark Ehrenreich, a Petaluma gardener who put in the community gardens for Petaluma Bounty, a non-profit that promotes a sustainable food system in Petaluma through community gardens, gleaning, food boxes and education.
He maintains that making cold compost with worms is actually easier than the more traditional method of composting with heat.
"Regular composting is really hard to do. You have to time it and take its temperature and turn it to make sure you have as good a product as you can," he said. "Whereas, with the worm bin, it doesn't stink. You don't have to turn it. As long as you keep the worms alive, they're going to eat 25 percent of their weight every day."
Your bin is not picky about what you feed into it — cereals, bread, fruits, vegetables, crushed eggshells, coffee grounds. You can also throw in chopped leaves, grass clippings, weeds, flower stalks and ground and crushed eggshells.
"It's really meant for getting rid of the stuff you put down the disposal or in the trash," said Ehrenreich. You're turning your waste into something useful."
Jack Chambers, owner of the Sonoma Valley Worm Farm, sings the praises of what he calls, "the noble worm."
In addition to breaking down organic matter, the worm's digestive process incubates and excretes microbes, which multiply. These microorganisms can make nitrogen more available to the roots of plants and inoculate the soil, making plants within it more disease- and pest-resistant.
Writhing just under the surface, the worms ingest soil and organic matter and leave tunnels that bring oxygen to plant roots and improve drainage, while breaking up heavy dirt clods and loosening the soil, according to the Sonoma County Master Gardeners.
Vermicomposters use the same red worms favored by many fishermen, a worm called Eisenia foetida.
Chambers primarily sells finished vermicompost. If you're squeamish about worms, you can buy it ready-made for $25 for a ? cubic foot bag, enough for 84 vegetable starts and some for your rose bushes. Chambers also has what you need to start your own home operation. Worms run $52.50 for two pounds. You can pick them up at the farm just outside Sonoma or have them delivered to your home via UPS.