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Monitor temperatures for pathogen and weed seed reduction

Heat is what makes compost safer. A long thermometer tells you whether the pile reached and held sanitising temperatures.

How

1. Push a long-stem compost thermometer into the centre of the pile and record the reading every few days.
2. Benchmark: US rules for treating sewage sludge by composting require 55 °C (131 °F) or more for 3 days in vessels or aerated static piles, or 55 °C for at least 15 days with at least five turnings in windrows. Use these as a reference standard, not a legal requirement for a home pile.
3. Extension guidance for home piles: aim for at least 55 °C (131 °F) for three days, keep 54 to 60 °C (130 to 140 °F) where you can, and turn the pile if the core goes above 71 °C (160 °F).
4. Turn the pile so the cooler outer material moves into the hot centre, then let it reheat. Repeat until it no longer heats after turning.
5. If it will not heat: mix in greens and turn. If it smells: add browns and turn. If it is dry: water and turn.
6. Cure for at least four weeks after heating stops, then screen through 6 mm (1/4 in) mesh and return lumps to a new pile.

Sources

1. 40 CFR Appendix B to Part 503: Pathogen Treatment Processes. Legal Information Institute, Cornell Law School (US federal regulation text), accessed 2026-11
2. HGA-01027 Composting in Alaska. University of Alaska Fairbanks Cooperative Extension Service, accessed 2026-11
3. Hot vs cold composting. University of Georgia Center for Urban Agriculture, accessed 2026-11
4. Composting At Home. US Environmental Protection Agency, accessed 2026-11

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