Worm Compost Bin

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Building your own worm compost bin can be very simple to do yourself. Here are a few suggestions and tips. You could use rubber storage bins, galvanized tubs, wood, tin, or plastic for bins.

Material: Rubber storage bins are cheap, easy to use and durable. Galvanized tubs are somewhat costly but will last forever. Wood will eventually be eaten, and plastic cracks easily, but either will do in a pinch.

Ventilation: Your worm compost bin should be well-ventilated, with several 3mm (1/8 inch) holes at the bottom (otherwise the worms will stay at the bottom of the bin and you may drown your worms). For example, you can build a worm bin out of a large plastic tub with several dozen small holes drilled out on the bottom and sides.

Size: The larger you make the container, the more worms it can sustain. Estimate 450 grams (1 pound) of worms (1,200) for every 30cm ( 1 square foot) of surface area. The maximum productive depth for your bin is 61cm (24 inches) deep because composting worms will not go further down than that.

Cover: The worm compost bin should have a cover to prevent light from getting in and to prevent the compost from drying out. Choose or make a lid that can be removed if your compost is too wet. Use a canvas tarp, doubled over and bungee-corded on, or kept in place with wood. Burlap sacks also work well, and can be watered directly.

Use 4 old car tyres: To make a four-tire wormery, create a base from old bricks or flagstones (must be flat and with as few cracks as possible). Place a layer of heavy newspaper on top of the bricks. Stuff four old tires with newspapers. Pile the tires on top of each other, with the first tire on the Sunday newspaper. Put some scrunched up paper or cardboard in the bottom to soak up any excess liquid. Fill the tire wormery with organic material (semi-composted is best). Add the composting worms (tiger or brandling species are best). Use a piece of board weighed down with bricks as a lid. The lid must be big enough to stop rain getting in. Harvest a tire's worth of fertilizer roughly every 8 weeks (during warm months).

Shredded newspaper for worm bedding.

Prepare the box for worms. Fill your worm compost bin with thin strips of unbleached corrugated cardboard or shredded newspaper, straw, dry grass, or some similar material. This provides a source of fiber to the worms and keeps the bin well-ventilated. Sprinkle a handful of dirt on top, and thoroughly moisten. Allow the water to soak in for at least a day before adding worms. You can also use Canadian peat moss, which is more expensive but yields a loamier vermicompost.


Get worms. There are several varieties of worms that that are bred and sold commercially for vermicomposting; just digging up earthworms from your backyard is not recommended. The Internet or local gardening club is your best bet for finding a worm vendor near you. The worms most often used, Eisenia foetida (Red Wigglers), are about 4 inches long, mainly red along the body with a yellow tail. Another variety to consider are Eisenia hortensis, known as "European Night crawlers." They do not reproduce quite as fast as the red wigglers, but grow to be larger, eat courser paper and cardboard better, and seem to be heartier. They are also better fishing worms when they do reach full size.         

Feed your worms fruit and vegetable scraps and refresh the bedding as necessary.

Maintain your worm compost bin. Keeping your worm compost bin elevated off the ground, using bricks, cinder blocks, or whatever is convenient will help speed composting and keep your worms happy. Worms are capable of escaping almost anything, but if you keep your worms fed and properly damp, they should not try to escape. A light in the same area will ensure your worms stay put. Sprinkle the surface with water every other day. Feed your worms vegetable scraps at least once a week. Feeding lightly and often will produce more worms (which is good when starting a new bin) and large amounts fed less often will fatten your worms (good for fishing). Add more cardboard, shredded newspaper, hay, or other fibrous material once a month, or as needed. Your worms will reduce everything in your bin quickly. You will start with a full bin of compost or paper/cardboard, and soon it will be half full. This is the time to add fibrous material.

Harvest the compost, using one of the following techniques.


Pull back the top layers of bedding to harvest the compost or check progress.

Put on rubber gloves, and move any large un-composted vegetable matter to one side. Then, with your gloved hands, gently scoop a section of worms and compost mixture onto a brightly lit piece of newspaper or plastic wrap. Scrape off the compost in layers. Wait a while giving the worms time to burrow into the center of the mound. Eventually you will end up with a pile of compost next to a pile of worms. Return the worms to the bin, do whatever you want with the compost, and repeat.

If you prefer a hands-off technique, simply push the contents of the bin all to one side and add fresh food, water, dirt, and bedding to the empty space. The worms will slowly migrate over on their own. This requires more patience, of course.

The last technique is to use a separator or shaker box.




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