If you're a city gardener with a limited number of plants, or if you don't have the time or space required to maintain a large compost bin, it's very possible to make a mini compost bin. A mini compost bin will require a small amount of outdoor space, and can be easily done on a patio, balcony, or even a front step. Your reward will be rich compost for your indoor and outdoor plants.
Purchase a plastic storage container at least 1 1/4 feet wide by 1 1/2 feet long (15 by 18 inches), and at least a foot deep. The size of the container will depend on your needs and your available space, but a container too small won't allow air circulation and will be difficult to stir.
Drill holes on all four sides of the plastic container. Space the holes about 6 inches apart. Drill 8 to 10 holes in the center of the lid. Turn the container over and drill two drainage holes in each corner of the container bottom. The bottom holes should be large enough for water to drain, but not so large that compost will leak out. If you don't have a drill, make holes with the tip of a sharp knife.
Tear a newspaper into strips 1/2 inch to 1 inch wide. Place the strips loosely on the bottom of the container, no more than 4 to 5 inches deep. Don't use any glossy color newspaper inserts.
Place "brown" (dry) organic material such pine needles, dry dead plants or leaves, egg shells, potting soil or dry grass clippings in the bin. Fill the container with brown material to a level of 1/3 to 1/2 full.
Cover the brown material with "green" organic material so that the container is nearly full, leaving enough space for stirring. Green material includes green grass clippings, vegetable and fruit scraps from the kitchen, and coffee grounds.
Place the container outside with the cover on. Stir the materials every week using a rake, shovel, long-handled trowel or other stirring tool.
Check the moisture of the compost every week by squeezing a handful of the materials. If the compost drips, stir the container daily to provide aeration. If the material feels dry and won't stick together when you squeeze it, add a small amount of water.
Process the compost for approximately three months, or until the compost looks like topsoil and has an earthy, rich smell. Test the compost by leaving a few handfuls in a sealed plastic bag overnight. If the bagged compost has an ammonia smell, allow the mixture to process for another week or two.