Sweet-smelling, crumbly compost is the most important ingredient in your garden. Soil is a living, breathing organism, and compost and other organic matter are the foundation of its microbial life. When you build a compost pile, you are mimicking nature's process of turning plant waste into a long-term soil builder. "Rodale's Ultimate Encyclopedia of Organic Gardening" provides an outline for the type of things you should put in a compost pile.
Rodale's separates compost ingredients into "greens" and "browns." Greens are materials with relatively high levels of nitrogen, which the microorganisms in your compost pile like bacteria and fungi need for reproduction. It is the basic building block of their cells. Green materials include manure, straw, coffee grounds, fresh plant matter like grass clippings and recently pulled weeds and table scraps. Table scraps should be plant-based; adding animal products like meat, cheese or eggs to your compost pile will attract skunks.
Compost ingredients classified as browns by Rodale's are high in carbon. Composting microorganisms need carbon to keep functioning and reproducing. Carbons are almost always plant materials, and many of them are yard waste. They include straw, leaves, pine needles and small branches. They are typically brown or yellow in color, bulky and dry. Paper is also one of the browns, but care should be taken to use unbleached or compostable (for example, corn-based) products to avoid introducing chemicals.
Your goal is to provide the right conditions for the billions of bacteria, fungi and other organisms in your compost pile to grow, reproduce and die. Too much carbon and the microorganisms run out of nitrogen and can't to reproduce. This slows down composting. Too little carbon and microorganisms won't have enough energy to keep going, and your pile will start to smell bad. Solve this problem by alternating a 2- to 3-inch layer of browns with 3- to 6-inch layer of greens and occasionally adding a sprinkle of good soil to any of the layers.
Ingredients need to stay wet for the plant matter in your compost to properly decompose. Start your pile in a shady spot so it doesn't dry out, and moisten it with a sprinkler or hose when you first make the pile and again during dry spells. Check the moisture level every few days. If no shady spot is available, cover your pile with a layer of straw to retain moisture. In dry climates, build a pile with a sunken top to help hold moisture, and in wetter climates build the pile in a mound to help drain excess water.
- "Rodale's Ultimate Encyclopedia of Organic Gardening"; Fern Marshall Bradley, Barbara W. Ellis and Ellen Phillips, eds.; 2009
- Natural Resources Conservation Service: Composting
Suzanna Didier's work appears in online publications including the National Geographic website, SFGate and Local.com. She is an avid cook who lives on a hobby farm, direct-markets organic produce to local restaurants and has taught at the preschool, elementary and college levels. Didier holds a Master of Arts in education from the University of Oregon.