Even if you have no room for a traditional outdoor compost pile, you can convert kitchen scraps into a nutrient-rich supplement for your soil all year long.
Vermiculture, or worm composting, is simple and efficient as the worms do most of the work for you. All you need are a container, a suitable location, some bedding material and, of course, worms. Red wigglers (Eisenia fetida) are the best worms for composting.
Select a location for your worm bin that’s out of direct sunlight. Worms like it dark. Avoid placing the bin in an unheated basement or next to a heat source. The temperature should be between 55 and 77 F.
Worm bins are available online and from garden supply stores in a variety of shapes and sizes. Some are multi-tiered while others sit on a tabletop, on the floor or inside a cabinet.
If you’re more of a do-it-yourself person, you can make your own using a container with a lid. Just be sure your design allows enough ventilation and drainage to let air in and prevent the bedding from becoming too wet. Lack of oxygen or soggy conditions can kill the worms. You can find directions for building a bin at go.uvm.edu/composting-worms.
To determine your needs, weigh your kitchen scraps for a week. One pound of worms will consume about one-half pound of scraps a day.
Feed your worms a combination of raw fruits and vegetables, coffee grounds (including the filter) and tea bags along with and cereal, bread and pasta in small amounts. Be sure to add finely crushed eggshells or another source of grit for their digestion.
Avoid meat, poultry, fish, bones, dairy, oils and fats as they may draw pests to the bin, foods with a strong odor such as onions and citrus. Never add pet waste to the bin.
For each pound of scraps per week, your bin’s bedding should have a surface area of at least one square foot. For example, if you produce one pound each day (seven pounds a week), you will need two pounds of worms, and your bin will need a surface area of at least seven square feet.
Red wigglers are sold by the pound and can be ordered online, purchased at a garden center or obtained from another worm composter. A pound will contain approximately 1,000 worms. The night crawlers in your back yard aren’t suitable for life in a composting container.
Appropriate bedding materials for your worm bin include a combination of shredded newspaper or corrugated cardboard, peat, coir (coconut fiber) or shredded dried leaves. Do not use garden soil as bedding.
Soak the bedding material in water to moisten it thoroughly, drain or squeeze out excess water and then add the bedding to the bin. Keep conditions inside the bin moist but not wet. Worms can drown if the bedding is too wet.
Empty the worms onto the top of the bedding. They don’t like light and will burrow down into the bedding.
To feed your worms, move aside some of the bedding to create a shallow hole. Drop food scraps in it (a half pound per pound of worms per day), then cover with about an inch of bedding material. This makes it easy for the worms to do their work and discourages fruit flies.
Soon the bedding material will be replaced by rich, dark compost. After several months, more compost than bedding will remain. Harvest the compost by separating the worms, replacing the bedding and returning the worms to the bin.
Deborah J. Benoit is a UVM Extension Master Gardener from North Adams, Massachusetts, who is a member of the Bennington County Master Gardener chapter.