The Basics
Composting is controlled decomposition. You're creating ideal conditions for billions of microorganisms to break down organic matter into humus — dark, crumbly, nutrient-rich material that improves every soil type. The process requires four things: carbon-rich material (browns), nitrogen-rich material (greens), moisture, and air.
Browns and Greens
Browns are carbon-rich materials that provide energy for decomposing organisms: dried leaves, straw, cardboard, newspaper, sawdust, and wood chips. Greens are nitrogen-rich materials that fuel microbial growth: fruit and vegetable scraps, fresh grass clippings, coffee grounds, and fresh plant trimmings. The ideal ratio is roughly 3 parts brown to 1 part green by volume. Too much green produces a slimy, smelly pile. Too much brown decomposes painfully slowly.
What NOT to Compost
Meat, fish, dairy, and oils attract pests and create odors that cold composting can't manage. Pet waste from dogs and cats carries pathogens that home composting temperatures don't kill. Diseased plants risk spreading pathogens to your garden through the finished compost. Weeds that have gone to seed may survive and sprout in your beds. Treated wood, coal ash, and synthetic materials have no place in a compost pile.
Building Your Pile
Layer browns and greens alternately, like a lasagna. Start with a coarse brown layer (small sticks, straw) on the bottom for drainage. Add green material, then browns, keeping the overall ratio around 3:1. Moisten each layer as you build — the pile should feel like a wrung-out sponge throughout. A pile at least 3 feet by 3 feet by 3 feet generates enough internal heat for efficient decomposition.
Maintenance
Turn the pile every 1 to 2 weeks with a pitchfork to introduce air. Anaerobic conditions (no oxygen) produce foul odors and slow decomposition. If the pile smells bad, it needs more air and more brown material. If it's not heating up, it needs more green material and moisture. A well-managed hot pile reaches 130°F to 160°F in the center, which kills weed seeds and pathogens.
Hot vs. Cold Composting
Hot composting requires active management (regular turning, moisture monitoring, proper ratios) but produces finished compost in 4 to 8 weeks. Cold composting is passive — pile materials up and let nature work at its own pace — but takes 6 to 12 months. Both produce excellent compost. Choose hot composting if you want fast results, cold composting if you prefer minimal effort.
Knowing When It's Done
Finished compost is dark brown to black, crumbly, and smells like earth. You shouldn't be able to identify any of the original materials. It's cool to the touch (hot composting finishes when the pile stops reheating after turning). Screen out any large chunks and throw them back into the next batch.
For composter equipment picks, see our Best Composters roundup. Compare tumblers and open piles in our Tumbler vs. Pile article.