By Michelle Wach, horticulturist, Colorado State University
Composting using worms is called vermicomposting. It's a fun composting practice, especially if you have limited space.
To construct a worm bin, use a plastic container with a lid. You will need a 1-foot-by-3-foot box to compost scraps from a family of four to six people. Fill the box with bedding material, using between 9 and 14 pounds. Bedding material can include chopped leaves mixed with compost and straw or shredded newspaper. Leaves alone may mat down, reduce air circulation and cause odor problems. You also can use shredded newspaper mixed with peat mosss or garden soil. After filling the box with bedding, moisten it with water until damp but not wet.
Now you are ready to add the worms. The nightcrawlers found outdoors are not suitable for vermicomposting. Redworms are preferred for indoor composting. In the Denver area, you might look for them at garden centers and nurseries. Some bait shops also carry them. You might be able to order them, but they can be sensitive to cold, so be certain they will arrive well-insulated-- and alive.
Redworms come to the surface to feed and then drag the food down into their bedding. Worms can eat their weight in organic matter each day. The box will yield some moisture so periodically drain the box to keep the worms from drowning.
You can feed the worms kitchen scraps, such as apple peels and lettuce. Do not feed them dairy or meat products because these foods attract flies and cause unwanted odors.
Worm castings should be removed once a month. Add scraps to only one side of the worm box. Feed them on the one side for several weeks allowing the other side of the box to be clear for casting removal.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010