Not every gardener has the space for a large compost pile, and not all municipalities allow backyard composting. The good news is that it's very easy to compost in a small space. Even if all you have is a patio or balcony, you can use this easy method of making compost in a trash can. And, if you need to compost on the sly, no one will be the wiser; they'll just see another trash can.
Building Your Trash Can Composter
Find or buy a 32-gallon or larger plastic or metal garbage can with a tightly closing lid. If rats are a problem in your area, a metal can is recommended.
Using a drill with a two- or three-inch hole saw, drill holes all the way around the trash can (lid, bottom, and sides), six to 12 inches apart. Cover each hole on the inside of the can with a patch of window screening, securing it with epoxy or silicone caulk.
Put your trash can composter in a convenient place. If possible, raise it up on a couple of bricks for air circulation below the can.
Using Your Trash Can Composter
A trash can composter can accept anything you would put in a standard compost pile, including:
- Fruit and vegetable peels and cores
- Leftover cooked veggies (as long as they don't have salt or butter on them)
- Produce that's past its prime
- Coffee grounds
- Tea leaves and tea bags
- Shredded newspaper
- Weeds, leaves, and spent flowers from the garden
Two things you should never add to your composter are meat and dairy, as they will spoil (and smell!) and attract pests. They can also introduce harmful bacteria that can cause illness.
It is a good idea to add a shovelful of garden soil to your compost. The soil contains all kinds of microorganisms that will consume the contents of your compost and break it down. If you don't have access to garden soil, don't worry. You'll still get compost, but it will take a little longer.
Maintaining the Best Ratio
Most expert sources on composting recommend using specific ratios of "green" and "brown" materials to make perfect compost. You may be able to get away with ignoring ratios if you have a large pile, but in a closed system such as a trash can, paying attention to the ratios of your materials is important.
If you have too many "greens," such as fruit and veggie peels, weeds, and grass clippings, the pile will stay too wet and will start to smell. If you have too many "browns," such as leaves, small twigs, shredded paper, and coffee grounds, the pile will just kind of sit there. Try for a ratio of at least 4:1 of browns to greens. You may see recommended ratios as high as 25:1, but the 4:1 ratio works well in a trash can composter.
Keeping Your Compost Moist and Aerated
In addition to a proper ratio of materials, you'll also need to make sure that your compost stays moist but not wet. In general, your compost should feel like a wrung-out sponge. Any wetter than that and it will start to smell because it has become anaerobic, meaning oxygen can't get to parts of the pile. If your pile dries out, it will still break down eventually, but it will take much, much longer than it should.
You'll also need to keep your compost aerated. In a traditional pile, this is done by digging into the pile and turning the contents every week or two. You can aerate your trash can composter by simply laying it on its side and rolling it around a few times. Do this once or twice a week until the compost is ready to use.