Optimum soil temperature for overwintering
I have heard that keeping the soil temps up during overwintering is as important as the air temperature.
What is a good soil temperature to aim for?
I will be overwintering in an unheated garage with south facing windows (lucky, right?). I say unheated but it usually doesn't get below freezing as I have HPS lights for orchids out there as well but they don't run 24/7. I will have the citrus trees on heat mats and want to keep them nice and warm but do not want to cook them.
So what to set the soil temperature?
Should it go lower in the night?