Composting 101 - What Can Be Composted?
The following items CAN be added to your compost pile:
- GRASS/LAWN CLIPPINGS
Actually, it's usually easier to leave grass clippings in the lawn, where they will decompose and benefit the soil directly. However, they can be composted, too. Be cautious to add grass clippings in very thin layers, or thoroughly mix them in with other compost ingredients, as they otherwise tend to become slimy and matted down, excluding air from the pile. - HAY & STRAW
Farmers are often very happy to get rid of spoiled hay bales that have been out in the rain, and will give them away or sell them at a low price. Be sure that any hay you plan to compost is well-moistened prior to addition to the pile.
- KITCHEN WASTES
Fruit and vegetable peels/rinds, tea bags, coffee grounds, eggshells, and similar materials are great stuff to compost. They tend to be high in nitrogen, and are usually quite soft and moist. As such, kitchen wastes need to be mixed in with drier/bulkier materials to allow complete air penetration. Avoid composting meat scraps, fatty food wastes, milk products, and bones -- these materials are very attractive to pests. - LEAVES
If you live in an area where autumn leaves are still thrown away as garbage, cash in on the bounty each year by acquiring your neighbors' leaves! Generally, leaves are an excellent compost ingredient. - WEEDS AND OTHER GARDEN WASTES
Many types of weeds and old garden plants can be composted. Avoid weeds that have begun to go to seed, as seeds may survive all but the hottest compost piles. Some types of weeds are 'pernicious weeds' and will resprout in the compost pile -- avoid using these unless they are thoroughly dead. Green weeds are (you guessed it) a 'green', while dead brown weeds are a 'brown'. - WOOD CHIPS AND SAWDUST
Stir sawdust thoroughly into the pile or use very thin layers. Coarse wood chips will very slowly decay, and are probably better used as mulch unless you have lots of time to wait. Be sure not to compost chips or sawdust from any sort of chemically-treated wood -- you could be adding toxics like arsenic to your pile if you do.
The following items CANNOT be added to your compost pile:
- CHEMICALLY-TREATED WOOD PRODUCTS
If you are considering composting sawdust, be sure of the origin of the sawdust. Sawdust from chemically-treated wood products can be bad stuff to compost. For example, pressure-treated wood (sometimes called CCA) contains arsenic, a highly toxic element, as well as chromium and copper. Avoid other chemically-treated wood productsthat have been treated with creosote or 'penta' preservative. - DISEASED PLANTS
Many plant disease organisms are killed by consistent hot composting, but it's difficult to make sure that every speck of the diseased material gets fully composted. It's best not to compost diseased plant material at all, to avoid reinfecting next year's garden. - HUMAN WASTES
Also called "humanure", human feces can contain disease organisms that will make people very sick. Composting human feces safely requires that the compost pile reach high (thermophilic) temperatures over a period of time. It isn't necessarily that difficult to reach these temperatures in a home compost pile, but the potential health costs of improper composting are high. - MEAT, BONES, AND FATTY FOOD WASTES
These materials are very attractive to pests (in an urban setting, this could mean rats...). In addition, fatty food wastes can be very slow to break down, because the fat can exclude the air that composting microbes need to do their work. - PERNICIOUS WEEDS
Morning glory/bindweed, sheep sorrel, ivy, several kinds of grasses, and some other plants can resprout from their roots and/or stems in the compost pile. Just when you thought you had them all chopped up, you'd actually helped them to multiply! Don't compost these weeds unless they are completely dead and dry. Remember also that composting weeds that have gone to seed will create weeds in next year's garden, unless a very hot pile temperature can be maintained to kill the seeds. - PET WASTES
Dog and cat feces may carry diseases that can infect humans. It is best NEVER to use them in compost piles. Some people do bury them 8" deep in the soil, but ONLY in areas where food crops are never grown.