Composting basics
Last reviewed September 2026 · written from public-domain USDA/NOAA data and Cooperative Extension references — see how we source data
Compost is the cheapest soil improvement there is and turns kitchen and garden waste into the one amendment nearly every garden wants more of.
Greens and browns
Aim for roughly equal volumes of "greens" (nitrogen-rich: vegetable scraps, coffee grounds, fresh grass clippings, spent plants) and "browns" (carbon-rich: dry leaves, straw, cardboard, wood chips). Too many greens turn slimy and smell; too many browns just sit there.
Chop or shred material and keep the pile about as damp as a wrung-out sponge.
Keep out
Meat, dairy, oil and cooked food (pests and smell in most home systems), pet waste, diseased plants, weeds gone to seed, and anything treated with persistent herbicide — including some straw and manures, which can damage a garden for years.
Hot vs cold
A hot pile — at least a cubic yard, balanced, turned every week or two — reaches 130–150°F, kills most weed seeds and pathogens, and finishes in one to three months. A cold pile is just a heap you add to and ignore; it works in 6–12 months and does not kill weed seeds.
Using it
Finished compost is dark, crumbly and smells like forest floor, with no recognizable food. Spread an inch or two on beds once or twice a year, use it as a quarter to a third of a raised-bed mix, or brew none of it into "tea" — just dig it in. The compost calculator works out how much a bed needs.