Spontaneous combustion is not likely to happen in home composting sites.
If a compost pile gets too hot … more than 160 degrees F, you can cool it down by
- Reducing the size of the pile
- Adding water to 55% moisture
- Mixing in course, bulky material such as woodchips.
Compost piles work best at temperatures between 130—150 degrees F. This may not happen with small compost piles or bins. Lower temperature will just take longer to compost.