How to Vermicompost: The Scoop on Worm Poop

Turn your food scraps into fertilizer by learning how to vermicompost with worms.

By Jo Harris
Updated on September 8, 2023
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by Kevin Fogle

Turn your food scraps into fertilizer by learning how to vermicompost with worms.

Charles Darwin estimated that an acre of garden space might hold 50,000 earthworms, and it’s easy to believe. After a good soaking rain, I hesitate to walk outside for fear of stepping on one of the soft, slimy invertebrates, and it’s difficult for me to consider how they can benefit us.

Since the classification system for earthworms has been in a state of flux since the early 1900s, it isn’t easy to get a fix on the number of earthworm species, but experts estimate more than 6,000 species of earthworms exist.

What Is Vermicomposting?

When it comes to vermicomposting — the process of using worms to convert organic kitchen waste into nutrient-rich organic compost — there’s one species that’s the odds-on favorite: Eisenia fetida, the red wiggler. There are three classifications of earthworms: litter, topsoil and subsoil. E. fetida thrives in the topmost layer of the earth’s decaying material, such as leaf litter. It doesn’t burrow through the matter, it actually eats its way through, consuming up to its own body weight per day. As organic material passes through the worm’s digestive system, it becomes laden with minerals and microorganisms. Voilà! Worm poop — known in scientific circles as vermicast, or worm castings.

Felicia McKee of Johnson City, Tennessee, is capitalizing on these lowly red wigglers. As a Certified Naturally Grown producer, a grassroots alternative to Certified Organic, she needs plenty of compost for her gardens. Fortunately, she has an abundance of vegetable peels, fruit rinds, egg shells, coffee grounds and more to feed the worms’ voracious appetite. Her payoff? Black gold — rich, environmentally friendly fertilizer that isn’t likely to damage water supplies.

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