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What Temperature is Your Worm Bin?

My university started a worm composting bin this semester. Everything appeared to be working well, we had lots of worm castings and tea. Then something seemed to happen…

Our bin was normally kept at 70 deg. F, until recently the temperature raised tremendously, and we are not sure why. The worms all migrated towards the edge of the plastic bin! We tried turning the compost in hopes of it reducing the temperature; however, it doesn’t seem to have made a difference.

What do we do? We are worried that our worms are going to die due to heat exhaustion!

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Nov 29, 2011
Creating a Cool Worm Bin
by: Compost Junkie Dave

What exactly do you mean by “raised tremendously”? Anything above 90 degrees Fahrenheit is typically fatal to worms.

Most composting worms are quite active when the temperature of their environment is kept between 55 and 75 degrees Fahrenheit (15 to 24 degrees Celsius).

Is there enough air circulation throughout the bin? Make sure their is adequate ventilation (via air holes, etc) within the bin itself. Could the air holes be clogged? If your bin has a lid, you may want to pull it aside for a few days and direct a fan with a gentle breeze on the bin to help evaporate any excess moisture. It’s this evaporation that helps keep your worms cool and content.

How moist is the material in the bin? Are you being conscious of adding more bedding at regular intervals? Worms don’t like their living conditions too moist, nor too dry. You want to achieve a good moisture balance and avoid the extremes.

Lastly, did someone add anything out of the ordinary to the bin recently, or move the bin into a new location (i.e. by a sunny window or vent)? If so, try to take it out of the sun, and away from all heating/cooling sources.

It’s hard to say with certainty what is going on in your bin, but hopefully some of the information above helps.

Anyone else have any suggestions?

Please keep us posted.


Nov 30, 2011
Hot Composted Worms
by: Gardener Ed

If the feed stock is too much (worms are over fed) and too rich it will ferment and produce heat. Try adding more carbon like shredded newspaper or dividing the contents in two to help dissipate the heat. You could spread the contents out on a plastic covered table to cool and then add the cellulosic material.

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