Great troughs, Lori! How do you over-winter them?
In answer to your question, my greenhouse is heated, but only to 1C. When the outside temperature falls to minus 15C or lower, the heater can't keep up with the heat loss, and the greenhouse temperature drops a few degrees below freezing. This is fine, though, since my aim was to emulate winter conditions the cacti would experience under a layer of snow. However, in the daytime, when the sun is shining the greenhouse heats up fast and I have a hard time keeping it to below 10C. Because of daytime solar heat, I need to water the cacti a couple of times during winter.
