Any plant residue can be composted, including weeds, lawn clippings, spent plants, leafy prunings and clippings, vegetable tops and vines, manure, sawdust and non-glossy newsprint.
Composting materials are divided into two types, green and brown. Green materials include green leafy plant residues like weeds, grass clippings, vegetable tops and flower clippings. Brown materials include fall leaves, straw, sawdust, wood chips and shredded newspapers. To speed up decomposition, use two-parts green material to one-part brown material.
Grass clippings can be composted, but it’s best to mulch them and leave them on the lawn. This recycles nutrients and decreases the amount of lawn fertilizer needed. If you compost your grass clippings, mix them with brown materials to prevent over-packing, which leads to obnoxious odors.
Brown materials composted alone require supplemental nitrogen to feed the decomposing bacteria. Add one-quarter to one-half cup nitrogen fertilizer per bushel of brown material. Woody materials also require extra composting time.
It’s probably easier to suggest materials you should NOT compost. Don’t use meat, bones, cooking-oil products, eggs and dairy products. These materials slow decomposition and may attract rodents and other animal pests. You also should not compost pet feces, as they may spread diseases.
It’s also inadvisable to compost diseased plants, insect-infested plants, and weeds loaded with seeds. These pest problems may survive the composting process and cause problems in the garden later.
For more information, see the following Colorado State University Extension fact sheet(s).