December 3, 2011

1 - Your compost pile does not need to be covered to continue the process of composting in the winter.

Yard and Garden - December 3, 2011


Do I need to cover my compost pile in the winter to keep it warm?

- Jamie D.


In most of New Mexico covering the compost pile is not necessary to hold heat. The composting organisms will generate their own heat if the mix of green (high nitrogen) and brown (Higher carbon) materials is appropriate and if there is adequate moisture in the compost pile. If the material in the compost is too coarse, twigs and other large debris, they may create large air spaces that permit heat to escape the compost. In that case, some covering may help, but it is important that oxygen is not kept from entering the compost. Oxygen is a critical factor in proper aerobic composting and allows the composting organisms to generate heat. Covering or shielding the sides of the compost pile will help reduce drying. Maintaining proper moisture is important and, perhaps, more difficult in the winter. The composting material should have the moisture content of a wrung-out sponge - damp but not soggy. Turning the compost pile periodically during the winter will cool it (initially), but by moving fresh material to the center of the compost pile and by aerating the compost, it will foster good microbial activity. This will quickly restore the heat needed for composting.Compost will proceed at a slower pace in the winter because temperatures (especially at the edges of the compost pile) will be lower, but composting will continue. Addition of kitchen vegetable waste will help keep the compost actively working during the winter. If possible, blend or puree some kitchen waste to reduce particle sizes and to add moisture when pouring the kitchen waste into the compost pile. This will also help maintain good conditions for composting. It is advised to keep a separate blender for this purpose. Grinding kitchen wastes is not essential, but it does help keep the compost pile working at the best rate possible.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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