Published on 08/31/17

Compost bin: Not too wet or too dry, not too hot or too cold

By Lisa Sehannie

Have you ever wondered how moist your compost pile should be or the ideal temperature for your compost? These are valid questions, and knowing the answers will keep your compost pile working at its best.

If you are a vermicomposter and, like me, you use worms to compost, these factors are even more important, as they can ensure the overall well-being of your little worm workers.

To maintain a healthy compost pile, you need to maintain the proper moisture level. Compost organisms are like people — both need water to survive and function at their best. Inadequate water will inhibit the activities of compost organisms, resulting in a slower compost process.

If the compost pile is too moist, water will displace air and create anaerobic conditions in the pile. The moisture level of a compost pile should be roughly 40 to 60 percent. To the touch, the compost pile should feel like a wrung-out sponge.

These same fundamentals apply to a vermicompost system. Adequate water is needed for the worms to function properly and survive. Vermicompost bedding should also be as damp as a wrung-out sponge.

The moisture level in a compost bin is easy to detect and, for the most part, easy to fix. If the bin is too wet, pools of water will accumulate at the bottom of the bin. Additionally, worms trying to escape from the bin or an unsavory smell are possible indications that the bin is too wet.

To fix a high moisture level, add more items that can absorb the water, such as newspaper or cardboard. Stop adding food items that have high water content, like fruits.

A bin that is too dry is equally unpleasant for the worms. Dried worms are a sure indicator that the compost bin doesn’t have enough moisture. To raise the moisture level, simply spray the bin with water from a spray bottle. Add food items with high water content.

A high temperature is desirable in a backyard compost pile, as it will accelerate the decomposition of materials. The heat can also aid in breaking down pathogens and weeds. The ideal temperature in a composting pile is 135 to 160 degrees Fahrenheit.

To increase the temperature of a compost pile, turn the pile weekly. Turning allows oxygen to flow, maintains the aerobic condition of the pile and regenerates heat.

The temperature in a worm bin is quite different than that of a compost pile. Unlike compost, worms prefer temperatures between 55 and 77 F. If the worm bin is outside, consider relocating it to a more temperature-regulated place, such as a garage or even underneath a sink in the house, during the warmer months.

For more information on maintaining a compost pile, refer to the University of Georgia Cooperative Extension Circular 816, “Composting and Mulching,” at

Lisa Sehannie is a Master Composter Extension Volunteer with University of Georgia Cooperative Extension in Clarke County, Georgia.

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