Materials You Can Compost at Home
You can compost most things that were once alive. The easiest rule is this: if it came from a plant or animal and will rot, it belongs in a compost pile or bin. Kitchen scraps like vegetable peels, fruit cores, coffee grounds, and eggshells break down quickly. Yard waste—grass clippings, leaves, small branches, and plant trimmings—makes up the bulk of most home compost. Paper and cardboard that have no plastic coating or glossy finish will decompose too, though they take longer than food scraps.
The speed at which materials break down depends on their carbon and nitrogen balance. Nitrogen-rich materials (called "greens") include fresh grass clippings, vegetable scraps, coffee grounds, and manure from herbivores. Carbon-rich materials (called "browns") include dry leaves, shredded paper, cardboard, straw, and wood chips. A working pile needs both: greens provide the nitrogen that microbes need to multiply and do the work, while browns give them the carbon they need to build their bodies and generate heat.
Key Takeaways
- Vegetable scraps, fruit waste, coffee grounds, and eggshells are safe to compost and break down in weeks to months.
- Yard waste like leaves, grass clippings, and plant trimmings make up the bulk of most home compost piles.
- Paper, cardboard, and wood chips compost well but take longer than food scraps because they are carbon-heavy.
- Meat, dairy, oils, and pet waste should not go in home compost because they attract pests or introduce harmful pathogens.
- A balanced pile needs both nitrogen-rich "greens" (food scraps, fresh grass) and carbon-rich "browns" (dry leaves, cardboard) to break down efficiently.
Kitchen Scraps That Compost Well
Nearly all raw vegetable and fruit waste can go into your compost. Carrot peels, onion skins, lettuce leaves, apple cores, banana peels, citrus rinds, and avocado pits all decompose without trouble. Cooked vegetables are safe too, though some people avoid them because they can attract pests if the pile is not hot enough. Coffee grounds and tea bags (remove the staple if there is one) are nitrogen-rich and break down fast. Eggshells take longer to decompose but add calcium to the finished compost.
Grains and bread can go in, but they may attract rodents if your pile is not enclosed or well-managed. The same goes for nuts and seeds—they will compost, but whole nuts take a very long time and seeds may sprout. Crushed eggshells and coffee grounds are among the fastest-breaking kitchen materials and are good additions if you want to speed up decomposition.
Yard Waste and Garden Materials
Leaves are the backbone of most home compost piles. Dry leaves are carbon-rich and can be shredded to break down faster. Fresh grass clippings are nitrogen-rich and heat up a pile quickly, though they can mat down and slow air flow if added in thick layers—mix them with leaves or other browns to keep the pile loose. Plant trimmings, dead flowers, and vegetable garden waste all compost well.
Small branches and twigs will compost but take years because they are dense. If you have a lot of woody material, chipping it first speeds decomposition significantly. Straw and hay are excellent carbon sources, though hay may contain weed seeds that survive the composting process. Wood chips from untreated wood are fine; avoid chips from treated lumber or wood that has been painted or stained.
Paper, Cardboard, and Other Household Items
Shredded newspaper, plain cardboard, and kraft paper all compost. Cardboard boxes break down faster if you wet them and tear them into smaller pieces. Avoid glossy or coated paper, which may contain chemicals that do not break down. Paper with colored ink is safe—modern inks are soy-based or mineral-based and do not harm compost.
Sawdust from untreated wood is a good carbon source, though it can pack down if added in large amounts. Wood ash from a fireplace or wood stove can go in small amounts, but too much raises the pH and can slow decomposition. Avoid charcoal ash, which contains substances that inhibit microbial activity.
Materials to Keep Out of Home Compost
Meat, fish, bones, and any animal products other than manure and eggshells should not go in a home pile. They attract rats, raccoons, and flies, and they can create odor problems. Dairy products like milk, cheese, and butter also attract pests and can create a sour smell. Oils, fats, and grease slow decomposition and can waterlog the pile.
Pet waste from dogs and cats should never be composted at home because it can carry pathogens harmful to humans. Diseased plants should be left out unless your pile reaches temperatures above 140°F (60°C) for several days—most home piles do not get that hot. Weeds with mature seeds and invasive plants like bindweed or bermuda grass may survive the process and spread when you use the finished compost. Treated wood, glossy paper, and anything with plastic coating do not belong in compost.
How to Layer Materials for Faster Breakdown
The most efficient compost piles alternate layers of greens and browns. Start with a 4-inch layer of browns (shredded leaves, cardboard, or wood chips), then add a 2-inch layer of greens (grass clippings, vegetable scraps, or manure), then repeat. This ratio—roughly 3 parts brown to 1 part green by volume—creates the right balance for microbes to work quickly without the pile becoming too wet or smelly.
If you add materials gradually (as most home gardeners do), straightforward mix new scraps with existing pile material rather than layering. Keep the pile as moist as a wrung-out sponge; if it dries out, decomposition slows dramatically. If it becomes soggy, add more browns and turn the pile to introduce air. A pile that is actively decomposing will feel warm in the center—that heat is a sign that microbes are multiplying and breaking down material efficiently.
Manure and Other Animal-Based Additions
Manure from horses, cows, chickens, and rabbits is nitrogen-rich and speeds decomposition. Fresh manure can burn plants if the compost is used before it fully breaks down, so let it age for at least three months before using it on vegetable gardens. Aged manure (more than six months old) is safe to use when ready. Avoid manure from animals treated with antibiotics or from animals fed grain treated with pesticides, as these substances can persist in compost.
Bedding material from herbivore enclosures—straw, wood shavings, or paper—can go in along with the manure. This combination creates a balanced mix of carbon and nitrogen. Never compost manure from carnivores or omnivores (dogs, cats, pigs) because it can harbor pathogens.
Frequently Asked Questions
Can I compost citrus peels and onions?
Yes, citrus peels and onion skins compost fine. Some people worry that citrus slows decomposition, but the effect is minimal in a balanced pile. If you add large amounts of citrus at once, mix it with browns and turn the pile to keep it aerated.
Will weeds in my compost spread when I use it in the garden?
Mature weed seeds can survive home composting if the pile does not reach high temperatures. Weeds without seeds or in early growth stages will break down completely. If you are unsure, leave out weeds with visible seed heads. Finished compost that has aged for several months is less likely to contain viable seeds.
How long does it take for compost to be ready to use?
This varies widely. A hot, actively managed pile with the right mix of greens and browns can produce usable compost in two to three months. A pile you add to gradually and turn occasionally may take six months to a year. Finished compost is dark brown, crumbly, and smells like soil.
Can I compost sawdust from my workshop?
Sawdust from untreated wood is safe. Avoid sawdust from treated lumber, plywood, or particle board, which contain glues and chemicals that do not break down. If you are unsure whether the wood was treated, leave it out.
What should I do if my compost smells bad?
A sour or ammonia smell means the pile is too wet or has too much nitrogen. Add dry browns like shredded leaves or cardboard, and turn the pile to introduce air. A rotten smell usually means the pile is waterlogged—improve drainage and add more carbon-rich material.