Introduction to Worm Composting (Vermiculture)

Ellen Sandbeck
Laverme’s Worms

Domestic vermicomposting is the art of using captive earthworms to transform kitchen waste into earthworm castings (aka poop). Those in the know often refer to earthworm castings as “black gold”. Vermicompost is extremely lively; it contains more than 100 times as many beneficial bacteria and fungi as can be found in the surrounding soil. It also contains plant growth factors and B vitamins, as well as high levels of soluble calcium, magnesium, phosphorus and potassium. Vermicompost is concentrated and considered by many to be nature’s most perfect fertilizer. As such, it should be used as fertilizer, not compost, and used sparingly. For example, plants that are heavy feeders such as squash, corn, tomatoes, and roses, will benefit from a cup or so of vermicompost mixed into the top layer of their soil. Lighter feeders should be given about a quarter cup or less. Legumes such as beans, peas, and lupines will not bloom if they are given worm compost, and neither will nasturtiums; under the influence of vermicompost, plants that require poor soil will grow thick, luxuriant leaves, but will not bloom.

Vermicompost is also extremely rich because each gallon of the finished product has been rendered down from twenty seven gallons of food waste. This impressive reduction-ratio can make it difficult to decide which is more valuable: the finished product, or keeping all those gallons of stinky, smelly food waste out of the landfill or the incinerator. Food waste alone comprises nearly 15% of our everyday waste, according to the Green Guardian.

Vermicomposting is simple if you have the right set-up and instructions, but nearly impossible if the bin is designed badly and the instructions are inadequate. After almost two decades of vermicomposting in my own home and setting up hundreds of bins for others over the past 18 years, I have learned my share about worms. Here are a few pieces of advice for aspiring vermicomposters:

1. A bin that is smaller than about 17 gallons will be extremely difficult to run because it is too small to gain any momentum.

2. Earthworms evolved underground and are well-adapted to their subterranean living quarters. If your vermicomposting bin has “air holes,” fruit flies (which can only hatch in the presence of air) will thank you; the worms will not.

3. Don’t ever use newspaper in your worm bin! Newspaper contains clay in the newsprint itself. The clay prevents the ink from spreading when the paper is printed. If you use newspaper in your worm bin, the clay, which is inorganic, will gradually build up and will make your vermicompost light colored, sticky, and will almost inevitably lead to a fruit fly infestation.

4. If a food is not healthy for you, it’s not healthy for your worms. Many humans may love french fries, potato chips, corn dogs and Twinkies, while worms generally avoid these pseudo-foods like the plague. If it’s fried or loaded with preservatives, it will take a really long time to break down in your worm bin. (And if a worm won’t touch it, why should you?)

In contrast to traditional composting methods, after the compostable materials have been introduced into the bin, the worms do all the work. In fact, vermicomposting is so efficient and odorless that it makes a fine indoor hobby.

Read Up

Laverme’s Handbook of Indoor Worm Composting, Laverme De La Terre, De La Terre Press, 1998

Act Locally

Laverme’s Worms: Duluth, MN 218-721-4422 or

Intro to Worm Composting

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