So, i am not totally green but this is my first grow that I'm running and in charge of. I was running a friends op for a while, cycling and flowering clones from his stock, watering, trimming, drying, the whole deal. The deal: myself and a trustworthy friend decided to go in together and grow some ganj. basically i am hosting the nursery, keeping copies of strains, sexing, popping new beans and what not. on his end, things will be flowered or veg waiting to flower. the flower room is in an old basement. 4' of concrete wall below ground level and 2' of brick, some of which is below, some above. most of the brick is insulated and panda film goes ceiling to floor. the problem is temps have been lower than anticipated. like in the 50s. Now this is with no lights running, but still i think its too low. We will be running a 400 watt mh for veg 18/6, and a 600 watt hps for flower (4x4) just to get things rolling. this spring we will expand out to 5.5'x10, maybe 12 and fortify the 600 with a combo light mover and COB frame. my worry at this moment is the 6 hours that no lights will be running, will temps get too low? we are doing more insulation in the ceiling tomorrow, but can only do so much. i may have jumped the gun a little trying to get things rolling but basically my current moms have out grown the space i have for them and i need to move them along in their life. what do you think the max low temp can be without significant harm? space is 16'x10x6'. weird shaped but is surrounded by either the earth or another room so there is some degree of stability. do i make sense? my brain is spinning! we've put a lot of time work and money into this and were so close! just need some realistic parameters until we can finish this off with a cherry on top. tyia for any constructive input!!!