For home composters with an outdoor bin, emptied coffee cans with their tight-fitting lids make an excellent place to temporarily store food scraps before taking them outside. However, for those without an outdoor composting bin, the coffee cans themselves can serve as indoor miniature composters. They're too small for conventional composting, but they can be used for indoor worm-bin composting, or vermicomposting.
Using a hammer and a nail, make 10 to 12 air holes in two rings, encircling the bottom outer inch of a coffee can that formerly held 2 to 3 pounds of coffee.
Fill the bottom inch of the can with gravel. Doing this allows air to enter the can but prevents soil from escaping and leaving a mess on your floor (see Reference 1).
Add a mixture of organic bedding materials, such as straw, shredded newspaper or cardboard, dry leaves or fine sawdust. Moisten the materials with water and then squeeze out the excess so that they're barely moist (see Reference 2, pages 19 and 20).
Fill the can loosely with the damp bedding.
Add a handful of red worms, also known as wrigglers, purchased from a bait shop or garden center. Ordinary earthworms won't thrive in a bin, but red worms flourish (see Reference 1).
Feed the worms regularly with small quantities of fruit or vegetable wastes, pushing them down into the bedding. Moisten the bedding lightly if it dries out. Secure the lid onto the can after each feeding, because the worms prefer to work in the dark.
Scrape the original bedding to one side of the can once it has largely become dark, rich compost. Only feed the new side for two weeks, until the worms have migrated there. Remove the compost for garden use, and top up the can with fresh bedding (see Reference 2, page 20).
- Keep your coffee-can composter in a place where the temperature remains moderate all year. Your worms won't appreciate extremes of heat or cold.
- One coffee-can composter makes an entertaining project for kids, but it won't make a serious dent in your household food waste. However, eight to 10 coffee-can composters consume approximately as much food waste as a conventional 2-by-4-foot bin.
Fred Decker is a trained chef and certified food-safety trainer. Decker wrote for the Saint John, New Brunswick Telegraph-Journal, and has been published in Canada's Hospitality and Foodservice magazine. He's held positions selling computers, insurance and mutual funds, and was educated at Memorial University of Newfoundland and the Northern Alberta Institute of Technology.