Government of New Brunswick

Let worms do the work! Composting with earthworms, or "vermi-composting," is great for apartment dwellers who don't have yard space, and for homeowners who don't want to hike through snowdrifts to a backyard compost bin. And many kids love keeping hundreds of wigglers for pets. There are several companies in Canada, who can sell you the bins, bedding, worms and all.

Covered Bin

Your worms can live in a plastic bin or wooden box, with plenty of airholes punched in the sides and top. Line the worm bin with nylon net to keep the small ones in. Holes in the bottom are needed for drainage, so you'll want a tray under the bin. Some people move their worms out to a balcony or yard in warm seasons. You may find it more convenient to have several smaller, more portable units rather than one large one. The size of the box will also depend on how much space you have.


Loam or black topsoil, available from garden centres, makes a particularly good bedding material. Bedding can also be shredded newspapers, soaked to soften the edges (the worms will eat this too, so avoid coloured inks and glossy paper) or a mixture of sawdust, peat, shredded leaves, and soil.

Fill the bin with about 30 cm (1 foot) of bedding, about as damp as a wrung-out sponge, not soggy and not dry. With a lid on the bin and regular feeding of the worms, maintaining the correct moisture level shouldn't be difficult.


It's true that earthworms aren't pets for the squeamish, but they are great little composters! You'll want the kind of worms that are sold for fishing bait, such as red wigglers or brandling worms, not ordinary field worms from someone's garden. Redworms normally live in barnyard manure piles, and feed on fresh organic material. Field worms are better at digesting things that are already well decomposed and aren't likely to survive in a worm bin on a diet of kitchen scraps.

Your valuable little redworms will live quietly in their dark box and multiply rapidly. Just bury your leftovers in their bedding after each meal. It is unlikely that you will have too much waste to compost: redworms will eat their own weight in kitchen scraps and bedding each day. The castings they produce are incredibly rich fertilizer and look like fine-textured soil. For each cubic foot of worm bin, plan on using 200 grams (approximately half a pound) of red wigglers (about 500, depending on their size).


Coffee grounds, vegetables and fruit are the recommended food for worms. A varied diet is important. Avoid bones, dairy products, meats, garlic and potato peelings. What doesn't cause odours or attract insects will simply take a very long time to break down. Eggshells are essential to keep the bedding from becoming too acidic for the worms. Dry them well, crush them, and sprinkle the tiny pieces over the top of the bedding.


Redworms will survive in temperatures from 5oC to 32oC (40oF to 90oF) but prefer it at or above room temperature. If you keep the worm bin outside in good weather, be ready to bring it in promptly when the temperature drops.

Harvesting the Castings

Removing the worm-compost couldn't be easier. You will notice that redworms hate the light. They'll wriggle down into their bedding whenever you take the lid off the bin. Every few months, when the castings outweigh the bedding that remains, place the opened bin under a very bright light and give the worms ten minutes to get well away from the surface. Then the coast is clear for scraping away the worm castings from the top layer.

When you start to see the worms again, keep the light on them and give them another ten minutes to go deeper still. And remove the next layer of compost. Keep going in this way until the harvest is done. Then fill up the bin with fresh bedding and start again.


Some people build special worm pits to take advantage of the worms' natural talents. To make a worm pit, all you have to do is dig a square hole 60 cm (2 feet) deep and set a bottomless box over it. The compost materials and worms are tossed in here. You can keep adding organic waste as it accumulates.

Keep the pile damp and dark, and the worms will do the rest. Remember to harvest your compost carefully, in bright sunshine, to save the worms from an unpleasant fate. They won't live long if they're stranded in ordinary garden soil, dumped there with a forkful of compost.

Here in New Brunswick, our climate is too extreme for redworms to survive outdoors through the winter. Some worm-owners in milder areas have good luck using very deep worm pits with thickly insulated walls, but it's risky business indeed. Better, bring the worms indoors to a bin as soon as a real frost threatens.