I am also having this problem...

I bought a HydroFarm heating mat for them...but it is no match for the cold temps...If I dont figure something out...my plants are dead

The stupid ass temps have stopped all growing, they have been the same hight for 3 weeks now.

I have some plants that are on week 8 of flowering...they have been the same size since week 5...at this rate...they should be ready at week 35