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Worms are not native to North America. About 20,000 years ago, our continent experienced an Ice Age, along with Europe and Asia. The phenomenon decimated the worm population, with the only survivors in parts of Turkey and the Mediterranean.

Over time, as Eurasians and Europeans began migrating to new lands, they brought plants for their new homes with them. Worms and other critters hitched a ride. On the East Coast of the U.S., these worms have changed the ecosystem because they eat the fallen leaves that trees also depend on for nutrition. This phenomenon is changing East Coast woodlands.

As the immigrant settlers moved across the country, so did their worms. In the Western U.S., worms have benefited the land, and consequently, the crops that people grow.

If you dig in damp soil, you will probably run across at least one worm. These earthworms (Lumbricus terrestris) live in the first 12 inches of soil. Their digestive systems turn soil into ever finer soil, and their castings improve the health of the soil. Worms also turn the soil, creating tunnels for water and roots. They won’t thrive in compacted soil.

Night crawlers (Eisenia hortensis) also live in the soil. However, when the air is damp, they come to the surface and feed on plants there. They are much bigger than red wigglers. Once, I put two night crawlers in a worm compost bin. When I cleaned the bin the following year, there were still just two night crawlers in the bottom of the bin. These worms had no interest in composting. However, some night crawlers from Europe and Africa will apparently do this work.

Red wigglers (Eisenia fetida, also known as fishing worms or manure worms), are the kings of composting. They are the worms you find under a stone, pot or pile of leaves. They only eat decaying matter.

Once, I put a layer of maple leaves in one of my bins. I seem to have raked up some maple seeds, too, because a week later I had a crop of baby maples in my compost. The worms ate the leaves but not the seeds, which were still fresh enough to sprout.


Red wigglers, the worms you find under a stone, pot or pile of leaves, only eat decaying matter.

Red wigglers eat or chew 90 percent of what you give them and that includes newsprint, plain cardboard, egg shells, daffodil leaves, spent flowers, vegetable leftovers, coffee grounds and animal fur. From these materials they produce compost, a mild fertilizer that you had a hand in.

Spread your worm compost over a garden bed, water it in, and the nutrients return to the soil. A lot of gardeners also put a little worm compost in the planting holes for their vegetables for an extra boost. I feed my potted plants with a handful of worm compost.

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African red wigglers (Eudrilus eugeniae) grow much longer than our red wigglers and eat more. The two types can survive side by side because they are not necessarily interested in the same decaying material. The African worms need higher temperatures, but I have corresponded with someone in Michigan who is successful raising them in his garage.

Other critters will move into your bins, too. Sow bugs or pill bugs will be the first to arrive, and their manure is just as good as worm castings. My compost-bin residents have included small toads, earwigs, slugs, snails, an occasional small snake (they like worms), a few lizards, ants and various flies. Most of these creatures coexist but I do get rid of the fruit flies.

This year, I am experimenting with putting compost bins in my raised beds, a technique common to African keyhole gardens. I put a compost bin in the middle of each bed so the worms can travel back and forth and hopefully fertilize the bed they are in. Only time will tell whether this experiment is successful, but I will report back.

Workshop: UC Master Gardeners of Napa County will host a workshop on “Rose Care” on Saturday, June 2, from 10 a.m. to noon, at University of California Cooperative Extension, 1710 Soscol Avenue, Napa. Roses will grow without any care. But they will thrive with a little TLC! Master Gardener rose experts will answer your questions regarding rose care at this popular forum. By June, the first spring blooms have faded, and many plants are beginning to show stress. Look for black spot, rust, mildew and aphids. Bring samples of what’s plaguing your roses. Online registration (credit card only); mail-in/walk-in registration (check only or drop off cash payment).

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UC Master Gardeners of Napa County ( answer gardening questions on Monday, Wednesday and Friday, 9 a.m. to noon, at the UC Cooperative Extension office, 1710 Soscol Ave., Suite 4, Napa, 707-253-4143.