Holy s man, those are some thick stems for the size of those plants....how long in veg?
Chomp
Overwatered maybe.? they look a little droopy. New growth looks a little yellow (lack of sulfur?)
i would second the overwatering. i noticed it first on page 2 but decided to finish reading the rest before saying something. maybe you would have gotten it fixed. you say it gets cold at night, that and damp soil is why all your leaves are curled up and so thick like that. the roots are too cold and damp. you need to either get the roots warmer or water less. at this age those plants should be monster sized but they arent. my suggestion is dont water again untill the pots are completely dry like tumbleweed dry or get a heating pad in there under your pots.
post up your plants in the infirmary. There is something wrong with them. Someone with more experience will be able to diagnose them better. Stihg been around here for awhile too. Maybe the bottom of the pot is soggy not enoughg drainage maybe.....