Winter compost piles are still working

Steaming compost is an indication that there are healthy organisms present. By actively managing your compost you ensure continued decomposition year around.

Wintertime concerns regarding compost are common. Compost piles that are actively managed will continue to decompose all winter long – just a bit more slowly. The active bacterial colonies change with the temperatures of the compost. Hot piles promote thermophilic organisms (those that like heat). Ambient piles are mesophilic, and the most common; and psychrophilic are organisms that are active in the cold.

  1. Many organisms continue to thrive under the snow in winter.
  2. Hot composting typically averages temperatures around 150 to 175 degrees Fahrenheit for a short time and requires a minimum size of 3 feet x 3 feet x 3 feet (5 feet is best) before cooling to ambient temperatures due to limiting factors. This method of composting requires more than just leaves to work effectively such as the addition of grass clippings and other nitrogen rich stocks.
  3. Do not confuse steam from your compost in the cooler months with fire. Compost piles will steam and actively managed piles often have the snow completely melted off throughout the winter.
  4. Covering your winter compost pile with straw or leaves can help insulate its core to keep it warmer longer.
  5. Avoid adding invasive plants and/or seeds to your compost piles in the fall and winter. Due to lower decomposition temperatures these plants may not be destroyed and will find your compost a great place to “overwinter”. Hot composting temperatures are required to destroy most pathogens and weed seeds.
  6. Do not compost near a body of water or shore of a lake or stream. Compost can contribute unwanted nutrients to the water.

For more information about composting and gardening visit Gardening in Michigan. For more information about the Clean Boats, Clean Waters program and aquatic invasive species contact Beth Clawson, MSU Extension Educator. To learn more about invasive organisms and invasive aquatic plants contact Michigan State University Extension Natural Resources educators who are working across Michigan to provide aquatic invasive species educational programming and assistance. You can contact an educator through MSU Extension’s “Find an Expert” search tool using the keywords “Natural Resources Water Quality.”

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