Maureen...I'm not real sure about the temps. Being my first year w/spectabilis...I guess I'll see. My others all do well w/my lowest heat setting of 58. When they are outside...when they first go out in the spring and in the fall just before they come inside...they might be exposed to temps into the low 50's but not usually for long. ??
Personally, I think I would try increasing the light a bit more and see if that does the trick. I think I'd be hesitant to expose any of them to temps that are too cool. ?? Again though...I'm new to spectabilis so it's all just a guess on my part right now. I'll know more next year at this time.