Food waste that breaks down in your compost pile
Most fruit and vegetable scraps compost well: apple cores, banana peels, carrot tops, lettuce leaves, onion skins, potato peels, and tomato ends all break down in a few weeks to a few months depending on pile temperature and moisture. Coffee grounds and tea bags (remove the staple from tea bags first) add nitrogen and decompose quickly. Eggshells take longer — three to six months — but they do break down and add calcium. Cooked grains like rice and oatmeal, dried beans, nuts, and seeds will compost, though they may attract pests if your pile is not hot enough or well-covered.
Bread, crackers, pasta, and other grain products compost but decompose slowly and can draw rodents and insects if exposed. Bury them in the center of your pile under brown materials like leaves or shredded paper. Fruit juice, vegetable broth, and plant-based milk (soy, oat, almond) can go in, but add them slowly so your pile does not become waterlogged. Stale beer and wine are fine in small amounts.
Key Takeaways
- Fruit and vegetable scraps, coffee grounds, and eggshells are the safest food items to compost and break down in weeks to months.
- Cooked grains, bread, nuts, and seeds compost but attract pests if not buried deep or covered well, so bury them in the pile center.
- Meat, fish, dairy, oils, and fats should never go in a home compost pile because they create odor, draw animals, and slow decomposition.
- Diseased plants and produce treated with pesticides can introduce problems to your finished compost, so check before adding.
Foods to keep out of your compost
Never add meat, fish, poultry, or bones — they decompose slowly, smell, and attract rats, raccoons, and other animals. Dairy products like milk, cheese, yogurt, and butter also smell and draw pests. Oils, fats, grease, and salad dressings coat pile materials and prevent air flow, which slows decomposition and creates odor. Avoid these even in small amounts.
Do not compost diseased plants or produce with visible mold or rot, because the pathogens may survive and spread to your garden soil. Produce treated with synthetic pesticides can also carry residues into your finished compost. If you are unsure whether a fruit or vegetable was sprayed, rinse it first or leave it out. Citrus peels, onions, and garlic take a long time to break down and can repel worms in a worm bin, so use them sparingly if you keep one.
How to prepare food scraps before composting
Chop or break larger pieces into smaller chunks — roughly the size of a walnut or smaller — so they decompose faster. A food processor or kitchen shears work well. Smaller pieces expose more surface area to bacteria and fungi, which speeds breakdown from months to weeks. Leave peels on citrus fruit and apples; the skin does not need to be removed.
Rinse produce that had pesticide residue or dirt, but do not add the rinse water if it contained soap. Layer food scraps with brown materials like shredded paper, dry leaves, or cardboard so they do not clump together. A ratio of roughly three parts brown to one part food waste keeps your pile balanced and prevents odor. If your pile starts to smell like ammonia or rotten eggs, add more brown material and turn it to add air.
Cooked food and leftovers
Plain cooked vegetables with no oil or sauce can go in your pile, though they decompose slowly. Cooked rice, pasta, and potatoes are fine in small amounts if buried. Avoid any leftovers mixed with meat, fish, dairy, or oil — the fat and protein attract pests and create smell. A small amount of plain cooked grain buried deep in a hot pile usually works, but if your pile is cool or you live where wildlife is active, leave cooked food out entirely.
Moldy or spoiled food is safe to compost as long as it is not meat or dairy. Mold is actually helpful — it is a decomposer that breaks down organic matter. Spoiled fruit and vegetables, stale bread, and rotten produce all compost well. The mold and bacteria already present will speed breakdown rather than slow it.
Composting in small spaces and worm bins
If you keep a worm bin indoors or in a small space, stick to the safest foods: fruit and vegetable scraps, coffee grounds, crushed eggshells, and shredded paper. Avoid cooked food, grains, bread, nuts, and citrus because they can attract mold flies or create odor in a confined space. Worms also dislike acidic foods like citrus and onions, so use those sparingly or not at all.
In a worm bin, chop food into very small pieces — smaller than in a regular pile — because worms work slowly and small pieces prevent mold blooms. Bury food scraps under the bedding so they are not exposed to air. If you see fruit flies, stop adding food for a week and cover the bin tightly. Worm bins work best when fed small amounts frequently rather than large amounts at once.
Seasonal and regional considerations
In warm climates where your pile stays hot year-round, you can compost a wider range of foods because heat kills pathogens and speeds decomposition. In cold climates where piles slow down in winter, stick to the safest items and avoid anything that attracts pests, because animals are more active when food is scarce. If you live where bears or large wildlife are common, do not compost any cooked food, grains, or anything with oil or fat — stick to raw fruit and vegetable scraps only.
Seasonal produce also matters: in fall and winter when you have more cooked squash and root vegetables, bury them deeper and add extra brown material. In summer when berries and soft fruits are abundant, your pile may become too wet if you add too much at once. Spread food scraps across the pile rather than dumping them in one spot, and add dry leaves or shredded paper to balance moisture.
Troubleshooting common problems
If your pile smells like ammonia or rotten eggs, you have too much nitrogen (food scraps) and not enough carbon (brown material). Stop adding food for a week or two and add shredded paper, dry leaves, or cardboard. Turn the pile to add air. If the smell is fishy or meaty, you may have accidentally added something you should not have — check for meat, fish, or dairy and remove it if you can find it.
If you see flies or insects, your pile is too wet or food is exposed. Bury all food scraps under at least six inches of brown material and let the pile dry out. If the problem persists, stop adding food temporarily. If your pile is not heating up and decomposing, you may not have enough food scraps relative to brown material, or the pile may be too small — aim for at least three feet by three feet by three feet to generate heat.
Frequently Asked Questions
Can I compost avocado pits and peach pits?
Avocado pits and other hard seeds take six months to a year or longer to break down, so they are not practical for most home piles. You can add them, but expect them to still be there when you harvest finished compost. Peach pits and cherry pits are similar. If you have a large pile that sits for over a year, they will eventually decompose.
What about composting nuts and nut shells?
Nuts and nut shells compost slowly — six months to over a year — and can attract squirrels and other rodents. Walnut shells are especially slow. Bury them deep in the center of your pile under brown material, or leave them out if wildlife is a problem in your area. Peanut shells break down faster than tree nuts.
Is it okay to compost expired food from the pantry?
Expired dry goods like flour, cereal, crackers, rice, and pasta can compost, though they decompose slowly. Expired canned goods should have the food removed and rinsed first — the metal or tin goes to recycling, not compost. Expired spices and condiments are fine in small amounts. Avoid anything with mold or that smells off, unless it is just old produce.
Can I compost food packaging like paper bags or cardboard?
Plain cardboard, paper bags, and paper towels compost well and are actually helpful as brown material. Avoid packaging with plastic coating, wax, or ink that says "not for composting." Shredded newspaper is fine, but glossy magazine pages are better left out because the ink may contain heavy metals.
What do I do with cooking oil and grease?
Never add cooking oil, grease, or fat to your compost pile. They coat materials, prevent air flow, and slow decomposition. Let grease cool and solidify, then throw it in the trash. If you have a lot of used cooking oil, some communities have recycling programs that turn it into biodiesel — check your local waste management website.