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Balanced compost comes down to one number: the carbon-to-nitrogen ratio. Aim for 25–30:1 overall. This chart gives you the C:N value of every common material plus recipes that just work.
1. Browns (Carbon-Rich Materials)
| Material | C:N Ratio | Notes |
|---|---|---|
| Wood chips | 400:1 | Very slow — best as pathway mulch or in small amounts |
| Sawdust (aged) | 300–325:1 | Use thin layers only; avoid treated lumber |
| Cardboard (shredded) | 350:1 | Remove tape; wet it before adding |
| Newspaper (shredded) | 170:1 | Soy inks are fine; skip glossy pages |
| Pine needles | 80:1 | Break down slowly; fine in moderation |
| Straw | 75:1 | Classic brown — fluffy structure adds airflow |
| Corn stalks | 75:1 | Chop or shred for faster breakdown |
| Dried leaves | 60:1 | The best free brown — stockpile in fall |
| Hay | 25:1* | *Borderline — fresh hay acts closer to a green |
2. Greens (Nitrogen-Rich Materials)
| Material | C:N Ratio | Notes |
|---|---|---|
| Horse manure | 25:1 | Often mixed with bedding; excellent activator |
| Cow manure | 20:1 | Compost 4–6 months before garden use |
| Grass clippings | 20:1 | Thin layers only — mats and goes anaerobic in clumps |
| Coffee grounds | 20:1 | A "green" despite the color; filters compost too |
| Fruit & veggie scraps | 15–20:1 | Bury in the pile center to deter pests |
| Alfalfa hay/pellets | 12:1 | Powerful nitrogen boost for a stalled pile |
| Chicken manure | 7–10:1 | Hottest manure — compost 6+ months, never use fresh |
| Blood meal | 3:1 | Sprinkle sparingly as a pile activator |
3. Hitting the Sweet Spot (25–30:1)
| Simple Recipe (by volume) | Approx. Blended C:N | Result |
|---|---|---|
| 2 parts dried leaves + 1 part grass clippings | ~30:1 | Reliable hot pile |
| 3 parts straw + 1 part chicken manure | ~28:1 | Fast, hot, farm-classic mix |
| 2 parts leaves + 1 part kitchen scraps | ~32:1 | Steady kitchen composting |
| 1 part sawdust + 4 parts grass clippings | ~35:1 | Works, but turn often |
👄 Smells Like Ammonia?
Too much nitrogen. Add browns (leaves, straw, shredded cardboard) and turn the pile.
🐌 Pile Not Heating?
Too much carbon or too dry. Add greens (grass, manure, coffee grounds) and water to "wrung-out sponge" moisture.
💧 Moisture Check
Squeeze a handful: a few drops = perfect. Dripping = add browns and turn. Crumbly dry = water while turning.
🌡️ Hot Composting
131–160°F for 15+ days (turning 5 times) kills most weed seeds and pathogens. Use a compost thermometer to verify.
4. What to Keep Out
| Avoid | Why |
|---|---|
| Meat, dairy, oils | Odors, rodents, slow anaerobic breakdown |
| Dog / cat waste | Pathogens that survive home compost temperatures |
| Diseased plants | Only safe in verified hot piles (131°F+); otherwise trash them |
| Black walnut leaves/twigs | Juglone is toxic to tomatoes and many garden plants |
| Glossy/coated paper | Plastic coatings and questionable inks |
| Herbicide-treated grass | Persistent herbicides (e.g., aminopyralid) can ruin compost for years |