First of all, the bin. If you’re using a plastic one, make it more rodent resistant by placing a sheet of hardware cloth under the bin to keep rodents from burrowing up. 16- or 20-gauge wire mesh: half-inch (1.25 cm) will keep rats out; quarter-inch (.63 cm) will keep mice out. In the picture you can see we even lined a door with mesh using those little plastic thingies. For wood bins, line the sides, bottom, and underside of the lid with the mesh. Metro Vancouver has produced some great plans for wood and wire bins, both single and triple bins. They also produce a good brochure on how to compost.
No need to place the bin in the sun, the added warmth can’t hurt, but if you really want to get things cooking, it’s more about what you put into the bin. Best to place the bin on the ground or grass so that the decomposers can come and go. If you place it on a cement patio, you may also get some leaching of compost liquids. If you live in an apartment or condo, worm composting might be the better option for you.
Vancouverites can visit the City Farmer Compost Demo garden for one on one training – they’re at 2150 Maple Street, open Mon to Sat 9 to 4. Or visit them virtually. They sell aerators (Wingdiggers) there too. And find out how you can get a bin here.
In a rodent resistant bin, create a base of three to four inches (7.5–10 cm) of twiggy material to promote aeration (do not mix into pile).
Alternate layers of green and brown materials; keep the layers two to four inches (5–10 cm) deep. Common green (nitrogen) and wet materials are grass, food scraps (uncooked fruit and vegetables, coffee grounds, filters, tea bags, and eggshells), and garden trimmings. Common brown (carbon) and dry materials are fall leaves, straw, and newspaper strips. Chop up larger materials for faster decomposition.
Whenever you add a food scrap layer, make sure you sprinkle it with soil and then cap off with a brown layer to prevent smells and flies.
Mix bin contents often (a minimum of once every two weeks). Use a compost aerator for the plastic bins, a pitch fork for larger bins. This introduces air and gets bin heating up again. Mix older materials with newer materials for faster decomposition.
Moisture content of bin should be like a wrung out dish rag. Only add water if pile is very dry after mixing. Not usually necessary on the wet coast of British Columbia.
Pile will shrink. Continue to add and mix until bin is almost full. This next bit is optional: place plastic or old carpet on surface of pile to retain heat and moisture.
Compost is generally ready to use when it looks like humus (after about two to three months). However, aging the compost for another one to two months is recommended.