High Elevation Gardening Web Log "Blog"

First, select a site on the ground, preferably in a sunny location and out of the wind. Sunlight will provide some heat on cold winter days, which will help increase the rate at which the organic materials are converted into compost by bacteria and fungi. A wind break will help reduce heat loss and drying. Contact with the ground can give access to worms and other creatures that participate in the decomposition. However, elevating the pile on a pallet can give access to needed oxygen.

Second, combine “green” and “brown” organic matter in a ratio of one-to-three by volume: one scoop of green to three scoops of brown. Green materials are rich in nitrogen and are moist. Brown materials are rich in carbon. The living decomposers need a balanced diet of nitrogen and carbon. Examples of green materials include fresh grass clippings, fruit and vegetable trimmings, coffee grounds and tea bags. Examples of browns are newspaper, straw, hay, dried leaves, and cardboard. Never place meat, dairy products, diseased plants or cat litter in the compost bin. When building the pile, alternate or mix the greens and browns rather than adding them in two distinct layers.

Third, create a compost bin or pile of one cubic yard, which is three feet by three feet by three feet. This size provides enough mass to insulate the center and help maintain the temperature needed by the bacteria and fungi. The decomposers will cause the temperature in the center of the pile to increase and the outer part of the pile will act as insulation.

Next, keep the compost pile damp. It should be about as wet as a wrung out sponge. If it’s too wet, add more browns. If it’s too dry, add greens or water. A dry pile will not heat up and decomposition will occur slowly. A wet pile will develop an unpleasant odor and will prevent oxygen from reaching the decomposers.

Fifth, insure the compost pile has adequate air. The microorganisms that decompose the materials need oxygen. Generally, the browns are somewhat bulky and provide air spaces. Crumpled newspapers and crushed cardboard egg containers can be used to create air spaces. If the pile settles, use a garden tool to loosen the pile to admit oxygen.

Finally, monitor the pile’s temperature. Compost piles can get above 130 degrees. The higher the temperature, the more rapidly composting will progress. In cold weather consider insulating the pile with straw or cardboard. Composting will occur slowly during the winter but can speed up in the spring as temperatures rise.

That’s it. A balanced mixture of greens and browns with water, oxygen and heat create the right environment for microorganisms to make compost quickly. What happens if the mixture is out of balance? Don’t worry, you’ll still get compost, but it will take a little longer. With experience, you can improve your composting recipe and skills.

By Paul Lambert
The author is a Master Gardener volunteer for Coconino County Cooperative Extension. For more information about the Master Gardener Program, call 774-1868 ext. 17 or visit our Web site: highelevationgardening.arizona.edu.