how we classify items
where the verdicts come from
Every verdict on this site is compiled from the published guidance of US university extension programs and the EPA — the same sources master-gardener programs teach from. Where programs disagree (and they sometimes do, especially on meat, dairy, and pet waste), we take the cautious mainstream position and put the disagreement on the page as a caveat rather than hiding it.
what the three verdicts mean
- Yes — safe and practical in an ordinary backyard pile with basic prep.
- Careful — compostable in some systems or with specific handling; the page spells out exactly which and how.
- No — either it won't break down, it contaminates finished compost, or it carries a health risk. Every "no" page includes a real disposal alternative.
the method matrix
Home composting isn't one thing, so every item is rated against six systems: hot piles (130–160°F, turned), cold piles, worm bins, bokashi fermentation, sealed tumblers, and municipal curbside programs. An item that's reckless in an open cold pile can be routine for a city facility that holds 140°F for weeks — the matrix is where those differences live.
browns, greens, and C:N numbers
Green/brown classifications and carbon-to-nitrogen ratios follow the ranges published in the On-Farm Composting Handbook (NRAES-54) and Cornell's composting literature. Where a material's published range is wide, we show a typical value and use the same number in the browns & greens calculator, so the item pages and the tool never disagree.
the safety line
Anything with human-pathogen risk — dog and cat waste, diapers, raw meat in open piles — gets the conservative call, always with the food-garden warning stated outright. We'd rather lose a technicality argument than seed roundworm eggs into someone's vegetable bed.
sources
- Cornell Waste Management Institute — Composting Resources
- Cornell Composting — C/N Ratio (Richard & Trautmann), which cites Appendix A, On-Farm Composting Handbook for published values
- On-Farm Composting Handbook (NRAES-54)
- US EPA — Composting at Home
- USDA — Composting basics and food waste guidance
- University extension vermicomposting guidance (consensus)
- Utah State University Extension: Sustainable Manure and Compost Application — manure by animal type, and why cat and dog waste stays out
- UF/IFAS Extension Sarasota County: Composting Dog Waste — the Fairbanks Soil and Water Conservation District method, and what it does not settle
- University extension and BPI guidance on certified compostable products (consensus)
- US university extension home-composting guidance (consensus across programs)
- Cornell Composting: Monitoring Compost pH
- University of Minnesota Extension: Interpreting your compost report (soluble salts)
- University of Maine Cooperative Extension: Is seaweed good to put in/on your vegetable garden?
- Colorado State University Extension: "A Philosopher's Guide to Composting Condoms" — a three-question test, worked through dryer lint
- LA Sanitation & Environment: Weekly Curbside Green Bin Collection (Organics) — accepted items
- Hasbro Consumer Care: Play-Doh Modeling Compound product information
Local rules trump everything here: curbside programs differ city to city, so when a page says "check your local program," that's the whole answer, not a hedge.