Proper Composting Temperatures

Compact Compost Tumbler

About Ideal Compost Temperatures

 Creating the ideal compost temperature is an important topic. Nature will decompose the raw materials in your compost at her own pace. However, her pace just might take a long time. So, let’s speed up the process. You do that by promoting the proper compost temperature inside your composter. The process of decomposition produces heat. A properly working compost pile is warmer than the surrounding air temperature. Therefore, your mission is to create the ideal temperature.

The temperatures should be measured deep in the center of the decomposing materials. A compost thermometer is available, to take this measurement.

Proper Compost Temperature Basics

  • In the beginning, your compost materials will be at or near the surrounding air temperature.  

  • As you bring the proper mix of green and brown compost material into a pile or a composter, the internal temperature will begin to rise.  

  • As it moves into the “Thermophilic” period, temperatures will ideally reach 135-160 degrees F. This range kills disease pathogens, weed seeds, spores, and more.

  • If the temperatures do not reach 130-160 degrees F, add more green materials, or a little nitrogen.

  • This high heat period usually lasts from 3 to 10 days.

  • Keep temperatures below 170 Degrees F. Above this point, bacteria are inhibited from decomposing materials, and the high heat can even kill essential bacteria.

  • The pile should be turned regularly, at least once a day. After turning the pile, the temperature will drop temporarily.

  • If the compost becomes too cool, add a little nitrogen, or nitrogen-bearing green compost materials.

Compost Size Affects Compost Temperature

The size of your compost pile or composter affects the temperature of the material. If the pile is too small, temperatures will not reach ideal levels.

A properly working compost pile should be at least 3′ X 3′ X 3′. This is required to obtain internal temperatures adequate to kill pathogens and weed seeds.

Did you Know? Spontaneous combustion can occur above 180 degrees F. Most home compost piles do not reach these levels. But it can happen.  If temperatures exceed 170 degrees, mix in brown composting materials, to help cool the pile a little.

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