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Compost System Design: Bins, Ratios, Turn Schedule, and Troubleshooting
Compost is the only garden input that improves every soil metric simultaneously: structure, water-holding, nutrient availability, microbial life, and disease suppression. But a smelly, slimy, frozen, or weed-seed-ridden pile is worse than none. Here is the foolproof system — bin design, feedstock ratios, turn schedule, and troubleshooting — that yields black gold in 8–12 weeks.
Bin design (three tiers)
Tier 1 — Single bin (small garden): 3×3×3 ft minimum (1 cu yd = critical mass for heat). Wire mesh, wood slats, or plastic tumbler. One bin = batch composting (fill, cook, harvest).
Tier 2 — Three-bin system (serious gardener): Bay 1 = fresh input, Bay 2 = active cooking, Bay 3 = curing/finished. Rotate monthly. Continuous throughput.
Tier 3 — Vermicompost (indoor/small space): Worm bin (Red wigglers, Eisenia fetida). Kitchen scraps only, no yard waste. Castings = premium fertilizer. Odorless if managed.
The golden ratio: 30:1 Carbon:Nitrogen
Browns (Carbon, ~30–80:1): Dry leaves, straw, shredded cardboard, newspaper, sawdust (untreated), wood chips, pine needles. Energy source for microbes.
Greens (Nitrogen, ~10–20:1): Grass clippings, kitchen scraps (fruit/veg), coffee grounds, tea bags, manure (herbivore only), fresh weeds (no seeds), green plant trimmings. Protein source for microbes.
Rule of thumb: 2–3 parts browns : 1 part greens by volume. Too wet/smelly = add browns. Too dry/slow = add greens + water.
The turn schedule (aerobic = fast + odorless)
| Week | Action | Target Temp |
|---|---|---|
| 1–2 | Build pile (lasagna layers), water to wrung-sponge moisture | 100–130°F (38–54°C) |
| 3–4 | Turn 1 (move outside to inside), check moisture | 130–150°F (54–66°C) |
| 5–6 | Turn 2, add water if dry | 130–150°F |
| 7–8 | Turn 3, check texture | 110–130°F |
| 9–12 | Cure (no turns), screen 1/2 in, store | Ambient |
Troubleshooting fast
- Smells rotten/ammonia: Too wet, too much N → turn, add browns, leave lid off
- Won’t heat: Too dry, too small, too much C → water, add greens, increase pile size
- Flies/maggots: Exposed food scraps → bury greens 12 in deep, cover with browns
- Weed seeds survive: Pile didn’t hit 140°F → ensure 1 cu yd minimum, turn on schedule
What NEVER goes in
Meat, dairy, oils, diseased plants, seeded weeds, pet waste, glossy/coated paper, treated wood ash, invasive roots (bindweed, bermuda grass).
One-line verdict
3-bin system, 2:1 brown:green, turn 3× in 8 weeks, hit 140°F — black gold that builds soil for decades.