According to the University of Illinois Cooperative Extension, you can produce finished compost with a compost tumbler in eight weeks or less. These short composting times occur because the tumbling action introduces additional fresh air to the oxygen-loving bacteria in the organic waste in your compost tumbler. Not only do the bacteria grow more quickly, they also consume your organic waste more quickly, which gives you prompt access to a nutrient-dense soil amendment for your vegetables and potted plants. Barbara Pleasant, co-author of "The Complete Compost Gardening Guide," suggests that newcomers to composting first build simple barrel tumblers from plastic trash cans.
Remove the lid from the top of the trash can and invert the trash container on the bare ground. Drill 10 to 12 drainage holes in the bottom of the trashcan, using a 3/8-inch drill bit and locating the holes at equal distances from each other to promote even drainage of excess moisture from your compost tumbler. Rest your hand firmly on the bottom of the trash can to secure it in place and drill 12 to 15 evenly-spaced ventilation holes along the sides of the container.
Flip the trash can right-side-up and fill it up with equal amounts of high-nitrogen materials (green waste, such as fresh grass clippings, vegetable peels and cow manure) and high-carbon materials (brown waste, such as straw, sawdust and dead leaves). Shred the pieces of waste into small segments that are less than 1 ½ inches in diameter to encourage quicker composting. Leave at least 3 to 4 inches of empty space at the top of the container to allow enough room for the organic waste to move freely when you turn the tumbler.
Moisten the organic waste with a gentle trickle of water from your garden hose, adding enough liquid to make the compost about as damp as a wrung-out sponge. Put the lid tightly on the top of the compost tumbler. Tip the tumbler on its side and turn it three to five complete rotations across the ground at least once every one to two weeks to produce finished compost in approximately two months.