How to Compost at Home

1. Pick a cool pile, a hot bin, or a trench.

How to compost at home is a choice of method, not a single bucket under the sink. University of Maryland Extension describes three practical routes.

• Cool pile: add scraps as you make them. It takes about a year. When the pile is about 3 by 3 by 3 feet, start another one and harvest the bottom of the first. Do not stack it over 5 feet. That much weight squeezes out air and the pile smells.
• Hot bin: fill a bin at least 3 by 3 by 3 feet all at once, with the right mix, water, and air. Do not keep tossing fresh scraps on top. Turn it when it cools, before it drops below about 100°F. A careful hot pile can finish in about six to eight weeks, then needs about two more weeks of curing.
• Trench: bury chopped fruit and vegetable scraps 8–12 inches deep in a garden bed and cover them with soil. Move the trench each time. This suits a fenced bed better than an open yard with raccoons.

Sheet composting, a layer of newspaper or plain cardboard under several inches of leaves or other organic matter, is a way to start a bed for next spring. It is not a potting mix. A tumbler stays small. Maryland notes that tumblers often become soggy if kitchen scraps outrun browns, and that they are usually too small to heat like a hot pile.

Put the pile or bin away from tree trunks so roots do not grow into it. The ingredient detail lives on compost browns and greens. Use that page when you are sorting leaves and scraps. Use this page to build and tend the pile.

2. Mix browns and greens, and leave some things out.

Microbes need carbon-rich browns and nitrogen-rich greens. Maryland treats dry leaves, straw, shredded plain paper, and wood chips as browns, and fruit and vegetable scraps, coffee grounds, and untreated grass clippings as greens. The EPA’s home-composting guidance is the other source for what a household pile should exclude. A practical starting mix already published here is about two to three volumes of browns for one volume of greens. That is a volume guide, not a laboratory carbon-to-nitrogen test. Mix the materials. Neat undisturbed layers are less useful than a blend.

Keep out meat, bones, cheese, milk, oils, peanut butter, pet feces, diseased plants, and weeds that have gone to seed. Plastic tea bags do not belong in the pile. Large amounts of wood ash change pH. Maryland also says not to add lime. Woody branches need to be chipped or they should stay out.

3. Keep it as moist as a wrung-out sponge, and give it air.

A dry pile stalls. A soggy pile smells, because it has no air. Add water in dry weather, and add dry browns and turn the pile if it is wet or smells of ammonia. Covering the pile in a heavy rain, or during a dry spell, keeps the moisture from swinging. Bury food scraps under browns so animals and flies have less to find.

Turn a hot pile when the center cools. Turn a cool pile once or twice a year. Maryland says not to turn a leaf pile in winter. Opening it then dumps the little heat it has. A cool center in summer usually needs a turn, not more food waste piled on top.

4. Use it only when it no longer looks like scraps.

Finished compost is dark, even, and crumbly, and it smells like soil. It should be close to outdoor temperature, and the original leaves and peels should be gone. Maryland’s extra check is a small sample in a sealed plastic bag: no condensation inside. Hot compost still needs that curing stretch of about two weeks after the temperature stops rising. The EPA’s home guidance, already used on the browns-and-greens page, is to cure at least four weeks after you stop adding fresh scraps. If the two sources seem to disagree, wait the longer time. A cool pile that still has fresh scraps on top is not finished just because the bottom looks dark.

Work finished compost into a garden bed, or spread about 2 inches as mulch around landscape plants, which is Maryland’s landscape figure. For containers, Maryland’s transplant idea is about half compost and half soilless mix, not a pot filled with compost alone. Our plant pages still name a potting mix. Follow the plant page for a pot. A raised bed’s volume is a separate measurement: raised-bed soil calculator. Tomatoes and other vegetables that will use the improved bed are in the vegetable library and in how to grow tomatoes.

Compost is not a pesticide and it is not a promise that every soil disease disappears. If you want the soil-word cluster later, organic matter and a soil profile are separate explanations. They are not this how-to.