What Can I Put in a Compost Bin?

One of the most common questions new composters ask is what actually belongs in the pile. The answer covers more ground than most people expect. Almost any organic material will break down eventually, but some materials compost faster, balance the pile better, and keep problems from developing. Here is a practical, thorough guide to everything you can confidently add.

Kitchen Scraps That Work Well

Most uncooked fruit and vegetable waste is ideal for composting. Banana peels, apple cores, carrot tops, lettuce leaves, melon rinds, and onion skins all break down quickly and add nitrogen. Coffee grounds are an excellent addition — they decompose fast and attract beneficial worms. Paper coffee filters go in too. Tea bags work if they are made from natural fibre; remove staples first. Eggshells add calcium and grit but break down slowly, so crush them before adding. Avoid cooked food, meat, and dairy at this stage — those belong in a different category entirely.

Garden and Yard Waste

Fresh grass clippings are a high-nitrogen green material that heats a pile quickly. Add them in thin layers to prevent clumping and matting. Spent plants from the vegetable garden are excellent as long as they are healthy — remove diseased material and roots from perennial weeds. Fallen leaves are one of the best browns available; shred them first to stop them matting. Hedge clippings and soft prunings chop down to a manageable size with shears. Flowers past their best add bulk and break down easily. Annual weeds that have not set seed are fine to include.

Paper and Cardboard

Cardboard and paper are underused browns that most gardeners have in abundance. Corrugated cardboard torn into hand-sized pieces breaks down reliably and helps create air pockets. Remove tape and any plastic coating first. Plain newspaper, brown paper bags, paper towels, and cardboard egg cartons all compost well. Avoid glossy or heavily inked paper — the inks and coatings can introduce unwanted chemicals. Shredded office paper is fine in moderation. Paper tends to mat into flat layers if added in large quantities, so mix it in with bulkier material rather than dumping a stack in at once.

Wood-Based Materials

Wood ash from untreated wood or log fires is a useful carbon source that also raises soil pH slightly. Add it sparingly — a thin dusting every few layers rather than a bucket at a time. Sawdust from untreated wood is an effective brown. Wood chips and shredded bark decompose slowly but add valuable structure. They are best mixed in rather than used as a thick layer. Straw is another excellent carbon source that creates good airflow in a dense pile.

Other Useful Additions

Hair and nail clippings from humans and pets break down slowly but contribute nitrogen. Natural fibre items — cotton or wool rags, hair ties, rope — are compostable if cut small. Spent compost from pots and grow bags can go into the pile for a second round of decomposition. Manure from chickens, rabbits, horses, or cows is a powerful nitrogen booster, though it should be added in layers rather than large clumps. Always balance wet or nitrogen-heavy additions with a layer of dry browns to maintain the right moisture and nutrient ratio.