What Can You Compost? The Definitive Yes/No List

What Can You Compost — And What Should Stay Out of the Bin?

You're standing at the kitchen counter with a handful of onion skins, a stale bread heel, and some citrus peels — and you're not sure which ones belong in the compost bin. You're not alone. According to a Penn State University survey, 42% of Americans say uncertainty about what can and cannot be composted is a major barrier to getting started. Meanwhile, the EPA reports that food waste makes up 24% of all landfill material — the single largest category — yet only about 5% of it gets composted.

The good news? Most of what you throw away from your kitchen and yard is compostable. The key is knowing which items break down safely in a home bin and which ones create problems like odor, pests, or lingering toxins. This guide gives you a clear, science-backed yes/no list so you can compost with confidence — no second-guessing at the bin.

What you'll learn in this guide:

• A complete yes/no list of kitchen scraps, yard waste, and household items you can compost
• The truth about controversial items like bread, citrus, meat, and coffee grounds
• Why the green-to-brown ratio matters brown vs green ratio and how to get it right without overthinking
• Items that should never go in a home bin — and safer alternatives

What Can You Compost? The Complete Yes List

Everything that goes into your compost bin falls into two categories: greens (nitrogen-rich, usually moist) and browns (carbon-rich, usually dry). You need both. Think of greens as the fuel that heats up the pile, and browns as the structure that keeps air flowing. The Cornell Composting program recommends aiming for a 25-30:1 carbon-to-nitrogen ratio by weight — which in practice means layering about 4 inches (10 cm) of browns for every 1 inch (2.5 cm) of greens.

Green materials (nitrogen-rich) you can compost: fruit and vegetable scraps, coffee grounds and paper filters, tea bags (remove staples), fresh grass clippings in thin layers, plant trimmings from healthy plants, eggshells (crush them for faster breakdown), and fresh chicken or rabbit droppings. These materials typically have a carbon-to-nitrogen ratio between 10:1 and 30:1, which means they decompose quickly and generate heat in the pile.

Brown materials (carbon-rich) you can compost: dry leaves (shred them to speed things up 2-3x according to UC Davis research), shredded cardboard and paper bags, newspaper printed with soy-based ink, straw (not hay — hay has weed seeds), untreated wood chips and sawdust, corn stalks, and natural-fiber clothing torn into strips. Browns decompose more slowly but provide the carbon backbone microbes need for energy.

Sources: Cornell Composting, UC Davis Waste Management, University of Minnesota Extension

Can You Compost Bread, Citrus, and Other Controversial Items?

Some of the most commonly searched composting questions are about items that fall into a gray area. Here's what the research actually says:

Bread and pasta: Yes, you can compost them. They break down in 2-4 weeks and have a C:N ratio around 15:1. The concern about attracting pests is valid but manageable — bury bread 6-8 inches (15-20 cm) deep in the center of the pile and cover with brown material. The University of Illinois Extension confirms that buried bread does not increase pest problems compared to fruit scraps.

Citrus peels: Absolutely compostable. The persistent myth that citrus acidity kills beneficial microbes has been debunked. UC Davis research found that compost piles with high citrus content reached target temperatures and decomposed on identical timelines to control piles. pH normalized by week six. Use citrus freely — the limonene in the peels even has mild antifungal properties.

Onions and garlic: Compost them without worry. They decompose in 3-4 weeks, and the myth that they repel earthworms is not supported by research. Oregon State University Extension found no significant effect on worm populations when onions were used in normal house worm binhold quantities.

Cooked rice: Yes, in small quantities. Mix it thoroughly into the interior of the pile and balance with browns to avoid attracting rodents.

Dryer lint: It depends. Lint from loads of 100% cotton or wool clothing composts in 2-4 weeks. Lint from synthetic blends (polyester, acrylic) does not break down and can persist in your soil for over five years, according to Oregon State University.

What Should You Never Put in a Home Compost Bin?

Not everything organic belongs in your backyard bin. The main reason comes down to temperature: home compost piles average 104-122°F (40-50°C), which is well below the 131°F (55°C) sustained for 3+ days needed to destroy dangerous pathogens like Salmonella and E. coli. Commercial composting facilities reach 140-160°F (60-71°C) — your backyard bin simply can't match that, according to data from the Rodale Institute.

Meat, fish, and bones: These decompose through putrefaction (anaerobic breakdown), producing hydrogen sulfide and ammonia — the rotten-egg smell that attracts raccoons, rats, and flies within hours. Bones take 3+ years to break down. If you want to compost meat, consider a bokashi system (anaerobic fermentation) as an alternative.

Dairy products: Cheese, butter, and milk fats coat organic matter feeding your soil with organic amendments with a hydrophobic barrier that blocks oxygen, according to Penn State Extension. This forces the pile into anaerobic conditions, producing sulfur odors and attracting pests.

Dog and cat waste: This is the most important "never" on the list. Cat feces can carry Toxoplasma gondii — a parasite whose oocysts require 131°F (55°C) for 30+ consecutive days to destroy, according to the CDC. No home pile sustains that. Dog waste carries similar pathogen risks. Use municipal waste disposal for pet waste.

Other items to keep out: treated or painted wood (leaches arsenic and chromium), glossy magazines (contain plasticized inks and clay coatings), coal or charcoal ash (contains sulfur oxides harmful to plants), and any material labeled as pressure-treated lumber.

How Do You Know Your Compost Is Working?

Finished compost takes 3-6 months in an actively managed bin, or 6-12 months if you take a hands-off approach. You'll know it's ready when the material is dark brown (not black), crumbly, smells like fresh earth, and you can no longer identify the original ingredients — except maybe a few stubborn eggshell fragments.

If your pile smells like ammonia, you have too much nitrogen — add shredded cardboard or dry leaves. If it's barely decomposing after several months and stays cool to the touch, you need more nitrogen — add grass clippings, coffee grounds, or fresh kitchen scraps. The Rodale Institute recommends a simple squeeze test: grab a handful and squeeze — it should feel like a wrung-out sponge, releasing just 2-3 drops of moisture.

Frequently Asked Questions

Can you compost bread in a backyard bin?

Yes. Bread breaks down in 2-4 weeks and has a carbon-to-nitrogen ratio of about 15:1, making it a nitrogen-rich "green" material. The key is to bury it 6-8 inches (15-20 cm) deep in the center of the pile and cover it with brown material like shredded leaves or cardboard. This prevents pest attraction. Avoid adding large quantities at once — a few slices at a time is ideal. If you're new to composting, start with small amounts until you're comfortable start composting at home managing your bin's moisture and temperature.

Can you compost citrus peels like orange and lemon rinds?

Absolutely. The common belief that citrus kills beneficial compost organisms is a myth. UC Davis research showed that compost piles heavy with citrus peels decomposed on the same timeline as citrus-free piles, with pH normalizing within six weeks. Citrus peels take 3-6 months to fully break down due to their tough outer skin. Chop them into smaller pieces to speed decomposition. The natural limonene in citrus peels actually has mild antifungal properties that can help suppress unwanted mold growth in your pile.

Is it safe to compost meat and dairy at home?

No — not in a standard home compost bin. Home piles rarely exceed 122°F (50°C), while destroying pathogens like Salmonella requires sustained temperatures of 131°F (55°C) for at least three consecutive days. Meat and dairy also decompose anaerobically, producing strong odors that attract rodents and raccoons. If you want to process meat scraps, consider a bokashi fermentation system, which uses anaerobic fermentation at room temperature before transferring the material to soil.

Can you compost eggshells?

Yes, but crush them first. Whole eggshells can take over a year to break down because they're primarily calcium carbonate — an inorganic mineral. Crushed shells decompose in 3-6 months and add valuable calcium to your finished compost, which benefits tomatoes, peppers, and other calcium-loving crops pepper companion plants. Rinse shells briefly to remove residual egg white, then crush by hand or run through a blender for the fastest results.

What can you do with food scraps you can't compost at home?

For meat, dairy, bones, and other items unsuitable for home bins, check whether your municipality offers curbside organics collection — commercial facilities reach temperatures high enough to safely process these materials. Bokashi fermentation is another option that handles meat and dairy in a sealed bucket using beneficial microbes. Some communities also have community composting drop-off sites. As a last resort, freezing scraps until collection day reduces odor in your kitchen waste bin.

Resources

• Cornell Composting — Compost Chemistry and C:N Ratios
• UC Davis — Making and Using Compost
• Penn State Extension — Home Composting: A Guide for Home Gardeners
• EPA — Food: Material-Specific Data (Food Waste Statistics)
• Rodale Institute — Turning Compost by Temperature
• Oregon State Extension — Compost in the Backyard
• University of Minnesota Extension — Composting in Home Gardens
• CDC — Toxoplasmosis: Causes and How It Spreads