66.5 N here. Whether greenhouse or outdoor cool "nights", light 24 hrs but sun transits north behind mountains 12am to 5am. Warmest nights of the season are mid to lower 50's F. Usually in the 40s, end of season 30s. Can be ridiculously cold at any time, seen it in the teens in Aug, wtf right? Not every year will be that weird, but the potential is there. This will be the first year I'll try a couple of plants outside the protection of greenhouse. My greenhouse is shed affair attached to the south side of cabin, cabin acts like a huge heat sink. Strains that are advertised as fast take 80 to 90 days in greenhouse. Briman's comment about kushes makes sense to me, and they do quite well in greenhouse. Actually most strains I've tried have done well, except the ones that are squat, densely leaved, and have huge juicy buds, oh they do well also but are mold magnets. So, my favs so far are tall plants with a good spread, fewer leaves and finish fast.