Composting doesn't have to mean spending hours maintaining an elaborate heap of organic waste in your backyard. If you're interested in using nutrient-dense humus to enrich your plant soil but don't have a lot of room for traditional compost piles and bins, then worm composting might be the composting method for your needs. Your worm bin can be as simple or elaborate as you wish, but make sure you meet the basic requirements to ensure a successful composting environment.
For compost worms to produce rich humus material, they need a place to work. Worms require a worm bin, which can be wood or plastic, depending upon what material is readily available; plastic containers need drainage holes in the bottom and ventilation holes in the sides to ensure that the bedding in the bin doesn't get too moist. Moist shredded newspaper works well for bedding, as long as the bottom three-quarters of the bin is full of the bedding material to ensure that the worms have plenty of room to do their work.
Canada's Office of Urban Agriculture suggests that worm bins measure 8 to 12 inches in height. As a general rule, 1 square foot of surface space in a worm bin provides enough room to process 1 pound of weekly food scraps. For example, if a household produces 4 pounds of food scraps in a week, then a container that measures approximately 2 feet by 2 feet would work well. One pound of compost worms typically consumes up to a half-pound of food scraps daily.
Collecting a bucket full of night crawlers in the backyard might save money, but these worms won't work in a compost bin. Most composters use the red worm species, Eisenia fetida, a small, wiggling composting worm known for its ability to scarf down large amounts of organic food scraps in a short time frame. Common names for E. fetida include red wriggler, manure worm and branding worm. Bait shops and online worm farms typically sell red wrigglers, generally at a cost of approximately $20 to $30 for a pound of them (approximately 1,000 individual worms)as of 2010.
Adding the right kinds of foods to a worm bin plays an important role in keeping odors at bay. Mild foods, such as potato peels, carrots, bananas and melons, as well as tea leaves and used coffee grounds, work particularly well, especially when buried beneath several inches of newspaper bedding. Smelly or rotten food, including meat, milk products and oily food, should not be used. Loren Nancarrow, co-author of "The Worm Book" states that sprinkling a gritty substance, such as plain dirt or crushed eggshells, into the worm bin once or twice each month helps improve the compost worms' digestion rate.
Mature compost is generally ready for collection approximately 10 weeks after starting a worm bin. The finished compost product generally looks like small clods of dirt. Some worm composters scoop the finished compost directly from the top of the bin in thin layers to ensure that they don't scoop out the worms with the compost. Others opt to simply dump the contents of the bin on a plastic tarpaulin in direct sunlight, which allows them to transfer the worms to a freshly bedded bin and harvest the compost all at once.