Temperature control for worm composting (or vermicomposting)

I want to do my worm composting ourdoors. Luckily there's a nice location far from any buildings (in case people object) and luckily my landlord is all for it. The problem is that the climate in Ottawa, Ontario, Canada ranges from -15C (5F) to 30C (90F) and worms prefer 4C (40F) to 27C (80F).

There are a number of things that I do that do not require costly energy:

  • use a shady location for summer cooling,
  • bury the worm composting bin for cooling in summer and warming in winter,
  • use geothermal heating and cooling,
  • reflect the sun's rays for cooling.
  • insulate the bin to conserve heat generated by composting
Click details about my shadily-located, buried, geothermally-air-supplied, reflective-surfaced compost bin all set for summer...
... and click here for details about my plastic covered, dry leaves and snow insulated compost bin all set for winter.

Some temperature measuring methods

Home Depot sells a handy remote thermometer. It consists of a hand control with the temperature readout and a long 10 foot wire which has the actual temperature sensor on the end. To monitor the temperature at the location near the bottom of the bin where the worms are, I bury the end of this wire. The readout is on the hand control which is outside the bin.

Burying the temperature sensor at the end of the long wire. Warning! You might want to wrap aluminium foil around the sensor since after leaving it in the compost for a few days it was damaged such that it no longer worked.
The hand control with the readout is on the left. The conventional thermometer on the right is showing outdoor temperature in the area of the bin.
Another view of the instruments.
Just throwing a thermometer in can measure the temperature at the top of the bin.
A temporary fix is to place a hot or cold object in the bin. In this case I've used a Formedica bag, a self-contained bag that you never open. You just put it in your freezer for a while to cool (or you heat it somehow). The contents then cool (or heat up) and you use it where needed. It's the same as using ice cubes but without having to make ice cubes.
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