Not every gardener has the space for a large compost pile, and not all municipalities allow back yard 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 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.
To start out composting, purchase the most inexpensive 32 gallon or larger plastic garbage can you can find. Make sure it has a lid. If rats are a problem in your area, consider purchasing a metal trash can. Then, using a two to three-inch hole saw bit and a drill, drill holes all the way around the trash can (lid, bottom, and sides) six to twelve inches apart. Cover these holes with window screening. Good strong duct tape or epoxy will work. Put your trash can composter in a convenient place. If possible, raise it up on a couple of bricks to get even more air circulation to the contents of the trash can composter.
So, what do you put into your trash can composter?
- 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
- Egg shells
- Shredded newspaper
- Weeds, leaves, and spent flowers from the garden
Never add meat or dairy to the composter, as it will spoil (and smell!) and attract pests. Besides that, your compost could then harbor harmful bacteria that could cause illness. It is a good idea, however, to add a shovelful of garden soil to your compost. The soil contains all kinds of microorganisms which 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.
Most books and articles about 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 like this, 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. I've seen recommendations as high as 25:1, but the 4:1 ratio works well in my trash can composter.
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, and you should have finished compost in two to four weeks.