A compost thermometer is a necessary piece of equipment for hot composting in a home garden setting and for commercial operators. It gives you an indication of the microbial activity, telling you when it needs to get turned and indicates if your carbon and nitrogen ratio of your compost materials were adequate. The higher the heat, the faster your materials will break down. But you don’t want it too hot to loose nitrogen and other nutrients and you also don't want your pile to go anaerobic.
With measuring the temperature you will see if you have added too much green material (gone too hot) or not enough (too cold) and if your moisture level was adequate (not enough moisture, no microbial activity). This will help you make a better compost the next time and will make you a better gardener.
Without a thermometer you are merely guessing and you cannot improve this valuable skill as a home or commercial gardener.

Please note: We suggest to store indoors or in a garden shed for a longer lasting product. Do not leave it in the compost pile overnight to avoid fogging and moisture inside the dial.

Measuring and monitor the center temperature of a thermal compost heap or windrow with our KoruKai thermometers. Take 2-3 readings per m2 heap and 3-6 readings for a windrow.

LOW (30-40 °C): 24-48 hours after the construction of a compost pile
MEDIUM (40-55 °C): 2-3 days after construction of a compost pile
HOT (55-68 °C): CONGRATULATIONS your pile is now officially a thermal compost. We aim to get to 55 °C within about 3 days.
TURN (68-74 °C):
- If you reach 68 °C within 3/4 days, you very likely need to turn your pile now as it will go higher than that.
- However if you have reached 68 °C on day 6 it could be your peak temperature. So monitor closely and decide if you need to turn or open up the center to reduce the temperature.
- A pile at 74°C needs to be turned asap.
Higher than 75 °C: A pile higher than 75 °C needs to be turned with utmost care because alcohols have been created, your pile is likely to be anaerobic and it can burst into flames.

Below a video how to measure the temperature of a compost pile.

It can also be used to measure the temperature of soil in spring which helps you decide on the time to plant out your first crops/seedlings.

Temperature is read from the tip and takes about 30 seconds. Take a few measurements per pile to get a more accurate reading.

This is why we make hot/thermal compost at KoruKai Herb Farm:

  • Kills weed seeds and other seeds from plants we don't want everywhere
  • Kills pathogens found in manure and plant matter
  • Kills plant diseases
  • Perfect ratio of carbon and nitrogen material to feed the soil food web and grow healthy plants
  • Improves soil structure: aggregates formation, stick soil particles together to make soil crumbly and easier to work with
  • Supplies nutrients ready for plants to take up, it is also charged so that nutrients and water can be held in the soil and don’t get washed out
  • Better drainage in heavy soils
  • More water storage in sandy soils
  • Increases aeration and the oxygen availability for the roots
  • Increases activity and the number of soil microorganisms
  • Makes soil darker and so it warms up earlier in spring
  • Produces healthy plants that are more resistant to disease and pests
  • Creates a complex soil food web

Read more about it in the link below.


Data sheet

1 stainless steel compost thermometer

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