Saturday, April 4, 2009

Temperatures In Large-Scale Vermicomposting Digesters

We get questions all of the time regarding the temperatures within our large-scale vermicomposting digesters (aka worm beds). It must be stressed that temperatures within these larger vc (vermicomposting) systems will be much different than those observed in smaller vc (home) units. Upfront I should also state that we have an enclosed facility that aids in controlling temperature swings. The building does have insulation and is minimally heated in the winter (building is heated to 48 F in the winter). Active ventilation assists in cooling the building during the warmer summer months.

  • Typically we see an average temperature (T) range between 70 degree F and 100 degree F throughout the year within the beds (measured about 4 inches from the bed surface). I can safely say that the beds really have never dipped below 68 degree F and never above 110 degree F for any significant length of time. At the those extreme temperatures (below 68 F and above 110 F) we start to worry about worm health and put remediation measures into place in order to adjust the temperatures to within an adequate acceptable range. It is also very typical to have a range of temperatures within a single bed at any one time. The ends of the beds exhibit different temp characteristics then other bed areas.

  • It's uncommon but you can get "hot spots" (greater than 110 F and less than 125 F) in the beds during the warmer periods of the summer. Hot spots may occur if feed material is placed over uneaten portions of the bed thus resulting in some form of composting action to occur. This is one reason to never overfeed your system. We precompost our feedstock (dairy manure) prior to feeding it to the worms. This action aids in reducing the energy in the material thus limiting the potential for it to reheat (composting) in the beds. We have also observed increased T in areas of greater worm activity (which makes sense).

Please comment or ask questions and I will do my best to answer or explain.


  1. What kind of heating system does your facilities use?

  2. The only heating system we use is overhead radient heaters (3 total). They are suspended about 7 feet above the beds. These are only used minimally during the winter.

  3. So, what about the irrigation system and the humidity of the material in the bed?, what is the % of humidity recomended for the bed?. Does the irrigation produces any lechate?
    thanks in advance

  4. I'm amazed at thee temperature range you show here. I've always read that it needs to be 45 to 78 degrees F.For heat in my flow through bin I run a decorative "rope light " encased in PVC pipe and placed fairly low in the bin, parallel to the harvesting blade.The heat radiates through the compost rather than heating the whole building.