Hot Composting: The Complete Walkthrough
This guide covers hot composting, rated a moderate task, typically taking 3–8 weeks.
Our printable card on hot composting covers the essentials at a glance — here's the fuller walkthrough.
Layer browns and greens
A hot compost pile relies on a good ratio of carbon-rich 'browns' (straw, dry leaves, cardboard) to nitrogen-rich 'greens' (kitchen scraps, fresh grass), built as a large enough mass to heat up.
Before You Start
A few things matter most here:
- A bay or bin at least 1m³
- A mix of browns (straw, dry leaves, shredded cardboard)
- A mix of greens (kitchen scraps, fresh grass clippings, manure)
- A garden fork for turning
- A compost thermometer (optional but useful)
Step by Step
The key things to get right:
- 1. Build the pile at least 1m³ in one go, layering browns and greens roughly 2:1 or 3:1 by volume.
- 2. Water each layer lightly as you build — the pile should be moist as a wrung-out sponge, not wet.
- 3. Turn every 2–4 days to keep oxygen levels up and heat even.
- 4. Monitor temperature — a good hot pile reaches 55–65°C in the first week or two.
- 5. Once the pile stops reheating after turning, let it cure for 1–2 weeks before use.
Troubleshooting
A few things matter most here:
- Pile won't heat up — usually too dry, too small, or too carbon-heavy; add moisture and greens, and ensure enough volume.
- Bad smell (ammonia or rotten) — too wet or too nitrogen-heavy; add more dry browns and turn more often.
- Pests attracted — avoid meat, dairy, and oily scraps; bury fresh additions into the centre of the pile.
- Slow to break down — pieces too large; chop or shred material smaller before adding.
Keeping It Going
Best time — can be started any time of year, though warm weather speeds the process. Duration: 3–8 weeks to finished compost with regular turning, versus months for a cold pile. Maintenance — turn every 2–4 days during the hot phase; monitor moisture throughout. Signs of success — dark, crumbly, earthy-smelling compost with no recognisable original material, and no further reheating after turning.
That's the full walkthrough. The printable A4 quick-reference card for this is on the main guide page below.