Food Scraps for Compost: What Kitchen Waste Can Go In

Roughly a quarter to a third of household trash is food waste, and most of it can be turned into garden soil. The best food scraps for compost are plant-based: fruit and vegetable peels, cores, coffee grounds, tea leaves, eggshells and stale grains. Chop them small, mix them with dry brown material such as leaves or shredded paper, and bury them in the pile. Done that way, a compost bin smells like a forest floor, not a garbage can.

The short no list matters too. Keep meat, fish, bones, dairy, grease and oily food, and pet waste out of a backyard bin. They attract animals, smell bad as they rot and can carry pathogens that home piles do not reliably kill.

Everything else on the kitchen counter is fair game, with a few caveats. Here is the full yes list, plus how to collect, prep and balance scraps so they break down fast.

The Yes List: Food Scraps for Compost

Plant-based kitchen waste counts as “green” material in composting terms. It is wet and rich in nitrogen, which feeds the microbes that heat the pile.

Fruits and vegetables

• Peels, rinds, cores and seeds from almost any fruit or vegetable.
• Wilted lettuce, carrot tops, broccoli stems, onion skins and potato peels.
• Melon rinds and corn husks (cut cobs into pieces; whole cobs take a long time).
• Overripe or moldy produce. Mold is part of decomposition and is not a problem in the pile.
• Pumpkins and jack-o’-lanterns, broken up first.

Coffee and tea

• Used coffee grounds, which are a nitrogen-rich green despite their brown color.
• Paper coffee filters.
• Loose tea leaves. Many tea bags contain plastic mesh, so tear them open and add only the leaves unless the bag is labeled compostable.

Eggshells

Eggshells add calcium and break down slowly. Rinse them, let them dry and crush them into small pieces so they disappear faster. Eggs themselves belong on the no list with other animal proteins.

Citrus, with a caveat

Orange, lemon and lime peels are fine in a regular outdoor pile in moderate amounts. Cut them up, because whole peels are slow to break down. Hold back on large quantities if you keep a worm bin, since worms dislike the acidity and oils.

Bread, grains and pasta, with caveats

Stale bread, plain cooked rice, oatmeal and plain pasta will compost. They also attract rodents and can turn slimy if added in clumps. Add them in small amounts, bury them in the center of a hot, active pile and skip them entirely if you have had pest trouble. Anything coated in butter, oil or sauce goes on the no list.

Other kitchen items

• Nut shells (except walnut shells, which contain a compound that can inhibit plant growth).
• Herbs and spices past their prime.
• Plain paper napkins, paper towels used for water or food spills (not chemicals) and uncoated paper plates. These count as browns.
• Cardboard egg cartons, torn into pieces, also a brown.

What to Keep Out of the Bin

Keep this brief list out of a backyard compost pile:

• Meat, fish and bones: strong odors and a magnet for raccoons, rats and dogs.
• Dairy: milk, cheese, yogurt and butter smell as they rot and attract pests.
• Grease and oily foods: fats coat other materials, slow decomposition and draw animals.
• Pet waste and used cat litter: can carry parasites and pathogens that home piles do not reliably destroy.

Also skip diseased plants, weeds that have gone to seed, and anything treated with chemicals. Some municipal compost programs accept meat and dairy because their industrial piles run much hotter; follow your local program’s rules if you use curbside collection.

How to Collect and Store Kitchen Scraps

A good collection system is what makes composting stick. Most households fill a small countertop container every two to four days.

• Kitchen compost bin: a 1 to 2 gallon container with a tight lid, ideally with a replaceable charcoal filter in the lid to control odors. Stainless steel, ceramic and sturdy plastic all work.
• Liners: compostable bags, newspaper or a sheet of paper towel in the bottom make emptying cleaner.
• Freezer method: keep a container or paper bag of scraps in the freezer. Freezing stops odor and fruit flies, and frozen scraps break down faster once thawed because ice crystals rupture cell walls.
• Empty often: in warm weather, take scraps out every two to three days to avoid fruit flies.
• Rinse the container each time you empty it and sprinkle a little baking soda in the bottom if smells linger.

How to Prep Scraps So They Break Down Fast

Small pieces have more surface area for microbes to work on. A melon rind cut into 1 to 2 inch chunks can disappear in weeks, while a whole rind may last months.

1. Chop large items such as rinds, cabbage cores and broccoli stalks into pieces about the size of your thumb.
2. Crush eggshells by hand or with the back of a spoon.
3. Break up clumps of coffee grounds and bread so they do not form dense, airless mats.
4. Drain excess liquid. A soupy bucket of scraps makes a soggy pile.
5. Carry scraps out and dig a hole in the center of the pile, drop them in, and cover them with at least 2 to 4 inches of browns or finished compost.

Balancing Greens and Browns So the Pile Does Not Smell

Making compost from kitchen waste fails most often because there is too much green and not enough brown. Food scraps are mostly water and nitrogen. Alone, they pack down, run out of air and start to rot anaerobically, which is where the sour, rotten smell comes from.

Browns are dry, carbon-rich materials: fallen leaves, straw, shredded paper, plain cardboard, sawdust from untreated wood and wood chips. A typical rule of thumb is two to three parts brown to one part green by volume. In practice, every time you add a bucket of food scraps, add two or three buckets of browns.

• Stockpile leaves in fall in bags or a wire bin so you have browns all year.
• Keep a bag of shredded paper or torn cardboard next to the outdoor bin.
• Aim for moisture like a wrung-out sponge: damp, but no dripping when squeezed.
• Turn or fluff the pile every week or two to add oxygen, especially after adding a large batch of scraps.

A well-balanced pile warms up in the center within days, often reaching 130°F to 150°F. That heat speeds breakdown and helps kill weed seeds. Finished compost from regular food scraps for compost typically takes two to six months, depending on how often you turn it and how warm the weather is.

Troubleshooting Kitchen Scrap Composting

• Rotten or sour smell: Too much green or too wet. Mix in plenty of dry browns and turn the pile.
• Ammonia smell: Excess nitrogen. Add browns, especially shredded paper or dry leaves.
• Fruit flies: Scraps are exposed. Bury every addition and cover the top with browns. Freeze scraps indoors before carrying them out.
• Animals digging: Check for meat, dairy, grease or bread on the surface. Use an enclosed bin with a lid, add hardware cloth under open bins and bury scraps deeper.
• Nothing breaking down: Too dry or too small. Water lightly, add more greens and build the pile to at least about 3 feet by 3 feet by 3 feet so it holds heat.
• Whole avocado pits or peach stones turning up: They are very slow. Remove them when screening finished compost and toss them back in the next pile.

Cost of Getting Started

Composting kitchen scraps is inexpensive. A countertop kitchen compost bin generally costs anywhere from about $15 to $50, and replacement charcoal filters are a few dollars each. A simple outdoor setup can be free if you build a wire or pallet bin, while enclosed plastic bins and tumblers often fall in the range of roughly $50 to $250. Many cities offer discounted bins or curbside food waste collection, which is worth checking before you buy.

When to Call a Pro

Backyard composting rarely needs professional help. Contact your city or county waste program if you want curbside food scrap collection, if local rules restrict outdoor bins, or if you have a persistent rodent problem near your pile, in which case a licensed pest control service can help. Cooperative extension offices and master gardener programs also run free composting classes and can troubleshoot a pile that will not cooperate.