room temp and fine white hairs???

i have a quick question? ... when my lights are off im my grow closet it gets real cold (like 50 or something) will that hurt my plants?... if so i need ideas on how to heat my grow room. (its a small closet and im kinda scared to put a heater in there (fire hazard) my next question is... my plant has small white hairs showing up on it... looks like its budding.. i think?... is it? (had 4 plants but my light fell on them and FUCKED THEM UP!!! so i rooted them and threw them out... only have one now... getting some more ready tho!

50F is too low, aim for 65-68f lights off. You can either use a tube heater, mini oil radiator or a heat mat designed for lizard tanks n stuff. I wouldn't use a heater with an exposed heating element.
Keeping the roots warm is most important, If they're kept warm the upper part of the plant will generally be fine. Wrap a blanket around the pot when the light goes untill you can sort something permanent.
Sounds like the white hairs are preflowers how old is the plant?

ill be honest... i dont know... about 3 or 4 months lol its roughly 36" tall i knew nothing about growing when i started i had 3... but they got chopped down by a falling flourescent fixture but its in a 8 ft tall closet with lights on the ceiling so its good... (gone be tall as hell!) i put it on 12/12 about 2 weeks ago (just learned i had to changet the light cycle)

i had a problem like this a while ago. i had one of those heater blankets and put it on the highest temp, this will keep them warm, but not too warm. be careful if youre doing hydro though so to not cause an electrical fire