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Worm compost is made in a container filled with moistened bedding and redworms. Add food waste and with assistance from micro-organisms, the worms will convert bedding and food waste into compost. Worm composting can be done year-round, indoors in schools, offices and homes. It is a natural method for recycling nutrients in food waste without odor. The resulting compost is a good soil conditioner for house plants, gardens and patio containers.
How You Do It
Buy or build a box with holes in the bottom. Fill the box with moistened bedding. Add the redworms. Pull aside some of the bedding, bury the food waste and cover it up with the bedding. Add one cup of soil or sand to provide grit for worms' digestive process.
What You Need
1. The Container
The container should be between 8-12 inches deep and provide one square foot of surface area for every pound of food waste per week (e.g., 6 lbs of waste requires a bin 2 feet by 3 feet or 2 bins 1 foot by 3 feet).
Depending on the container's size, drill 8 to 12 holes (3/16- 1/4 ") in the bottom for aeration and drainage. A plastic bin may need more drainage - if contents get too wet, drill more holes. Raise the bin on bricks or wooden blocks for air circulation. Place a tray underneath to capture excess liquid, which can be used as liquid plant fertilizer.
Worms like a moist, dark environment. Their bodies are 75 to 90 per cent water and worms' body surfaces must be moist for them to breathe. Cover the bin to conserve moisture and provide darkness. Indoors, place a sheet of dark plastic or burlap sacking on top of the bedding. Outdoors, use a solid lid to keep out unwanted scavengers and rain.
Worm bins can be located in the basement, shed, garage, balcony or kitchen counter. They need to be kept out of the hot sun, heavy rain and cold. When temperatures drop below 40 degrees, bins should be indoors, heated or well-insulated. The container can be heated with an electric heating cable placed in the bottom third of the container. To insulate, surround the container with rigid Styrofoam.
2. The Worms
You can get your worms from a compost bin, purchase them or find a horse stable or farmer with an aged manure pile.
For one pound per day of food waste, you'll need two pounds of worms (roughly 2,000). If you are unable to get this many worms at the start, reduce the amount of food waste until the population increases. And the population will increase. Redworms mature sexually in 60-90 days and can then produce cocoons which take 21 days to hatch baby worms. Once they start breeding they can deposit two to three cocoons per week with two baby worms in each cocoon. The limits on their reproduction include availability of food and room to move and breed. So worm populations don't usually exceed the size of the container.
3. The Bedding
Fill the bin with a mixture of damp bedding so the overall moisture level is like a "wrung-out sponge." Lift the bedding gently to create air spaces. This maintains aerobic activity, helps control odors and gives the worms freer movement.
4. The Food Waste
Pull aside the bedding, bury the food waste deep and then cover it up with the bedding again. Divide the bin into three or four imaginary sections (larger bin, more sections) and bury successive loads in different locations in the bin. Keeping a chart of burial sites can be helpful. Weekly food waste will help determine the size of bin and number of worms you'll need. Collect food waste in a container and weigh it. Do this for two weeks to get an estimate of average food waste. Your bin should provide one square foot of surface area for every pound of food waste per week. And you will need two pounds of worms for every pound of food waste per day.
Harvesting Your Compost
After six weeks, the bedding will be noticeably darker with worm castings. After two and a half months have passed, there will still be some of the original bedding visible in the bin plus brown and earthy-looking worm castings. Although food waste is being added regularly, the bedding volume will gradually decrease. As more bedding is converted into castings the worms will begin to suffer. It is time to decide whether you want to do "some fuss" or "more fuss" worm composting.
"Some Fuss" Harvesting
"More Fuss" Maintenance
Adapted with permission from an article published by the Greater Vancouver Regional District.
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