According to Mary Appelhof, author of "Worms Eat My Garbage," worms in an indoor compost bin can produce up to 15 gallons of finished compost in one year. Also called vermicomposting, indoor composting with worms is an easy and affordable way for you to give your potted plants and vegetable garden a year-round supply of nutrient-rich soil conditioner.
In order to compost with worms indoors, you'll need red worms, a worm bin, bedding and food scraps. The two main types of red worms used for worm composting are Eisenia fetida and Lumbricus rubellus. You can acquire these worms by the pound from other worm composters, online worm farms or even an old manure pile. Most worm bins are either plastic or wood, often depending upon what materials you have available when you build your bin. According to Canada's Office of Urban Agriculture, any indoor location is fine as long as you make sure the temperature is between 40 and 80 degrees F. Common choices for worm bedding include shredded newspaper and cardboard as well as old leaves.
The size of your worm bin plays an important role in determining the success of your indoor worm composting. Try to use a container that is about 12 inches tall so you can reach into it easily. Allow about 1 square foot of surface area for every pound of food scraps your household produces in one week. According to Mary Appeldorf, 1 pound of worms (about 1,000 worms) can consume about 1/2 pound of food waste per day. Thus, if you produce 6 pounds of food waste in one week, you'll want to get about 2 pounds of red worms for a container that is about 2 feet by 3 feet. If you produce a lot of waste, consider using several smaller bins so you can move them around your house more easily.
Be careful when selecting food to put in your indoor worm bin; adding the wrong food can cause offensive odors and attract rodents and insects to your home. Common foods that shouldn't produce problems include most fruit and vegetable scraps, tea bags and coffee grounds. Canada's Office of Urban Agriculture suggests that you avoid potentially problematic foods such as dairy products, grains and meat products.
Worms can produce finished compost in about 12 weeks. When you compost indoors, this can take place at any time of year. Once you have your worm bin set up, add food on a daily basis in small amounts, making sure that you bury the food scraps beneath about 3 to 4 inches of bedding and you keep the bedding moist. As the weeks go by, your worms will produce castings, a waste material that mixes with the bedding to produce your finished compost.
Indoor composting with worms provides you with a range of benefits over traditional composting methods. According to Mary Appelhof, worm compost has higher nutrient levels than traditional compost. Indoor worm composting also requires less space and is more convenient than other types of composting, because you don't even have to venture outside your home. Additionally, the movements of the worms themselves help aerate the compost, eliminating the need for you to turn the compost yourself which you typically have to do with traditional composting methods.