Low temperatures

Hello all,

Got four auto's under cfl/led, ironically because my HPS was way too hot in the summer, well now, at my canopy were looking at 21 C with lights on and around 19 C at the level of the pots? this is too cold isn't it, i've noticed slow growth and i imagine this is the culprit, should i stuff my HPS in there?? and lets the plants deal with more like 27 C in the tent? though in the summer it went to 33 C!!!

if not should i get a heater?

EDIT: thanks for any help i can get

69-70° (21c) is a bit on the cool side you dont want it to drop any lower from there. I would try the hps again 80° (27c) isnt to bad. my first two runs were 80-85 with lights on and I didnt have problems. now I like to keep my temps around 75 lights on.

thanks a lot i thought so, i just havent had much experience with cold, always too hot!

ive read that cold soils make it difficult for the plant to absorb phosphorus, could this be why my plants feel like their root system is weak? (the plant seems weak above ground, wobbles easily in the pot like it isn't being supported fully)

thanks again for the 'elp

Ive read the same but havnt had a problem with it. My ac's blowing air into my tent, and at floor level the temps 65°. My night temps at canopy drop to 65° also.

as far as plants seeming weak how old are your plants and what size pot are they in?

If you are growing autos just leave the lights on 24/7. Not having a lights out will keep the temps from falling down during that time. You could also add in some more cfls till you get the desired temps if you don't go back to the hps.

Go back to your HPS and monitor your temps. Can you leave the tent door ajar to keep it cool?
If not, get a small electric fan, 4 or 5-incher should do it.

Good luck, BigSteve.

thanks for the responses y'all,

yes i've been thinking about putting that hps back in for sure, i was getting to 33C in the summer, when ambient temperatures were 26 indoors, pretty hot, now it's more like 18C in the house so i reckon i'll get away with it, could have my LED as well and just dump the fat cfl...

as far the plants seeming weak, dont worry, i cant explain it too much better than that, more of a hunch than me knowing exactly how well rooted a plant should feel!

one more thing i think ive got a serious case of phosphorus deficiency on one plant, reddening and purpling on leaves and very slow bud growth, though its the frostiest of the lot by miles, i'll post a picture tomorrow because i cant seem to find a good picture of that, even though the descriptions all says those are some of the effects, p.s it's cold but not cold enough for purple and none of the others have it.

eh...what?