Note Kale & Brussels Sprouts on the left (transplant from generous neighbour) & Lovage in the center (in above photo). Peas and Swiss Chard are just starting to break the surface (can't see in this photo).
Part of the experiment was to test the cold frame in frost conditions with a sensitive plant like tomatoes. Frost was predicted that night, so last minute scrambling resulted in blankets and tarps over the windows and a 60W bulb placed inside to provide a heat source (a method used successfully by my aunt). I had plans to put a fan inside as well to circulate the heat, but due to limitations with the extension cord and time, only the light was used in the end.
A high-low recording thermometer is on the list of items to purchase for future experimentation. If anyone can recommend a thermometer please let me know. All the ones I've seen so far at Canadian Tire are battery operated digital and I'm trying to find a non-battery type. Searching just now there is one at Lee Valley. I have not been there yet as it is a bit far by bicycle. I suppose a digital thermometer with an indoor alarm for low temperature might be handy too, maybe establish trending into the computer... OK maybe too high-tech for this low-tech garden operation!