Mine took off as well and is totally ridiculous. I did not top or train it and it grew over a foot in the last week and I don't think it is done yet. I have to keep moving the light up every day. It is over 3ft now.@olbobcat marathon coming alive. Gonna be last to flower but she's got some topsView attachment 1412574
You can always put a submersible fishtank heater in there. My growroom is warm from the lights very rarely under 76 and that is the basement. I was -12 the other day and I was sweating down there.Just for my record, it's been below freezing here for weeks and the autopot rez is currently 45 degrees. Doesn't seem like the plants have a problem with it. Personal theory is low temp doesn't matter in the rez since it'll warm in the pots before the roots have a problem with it