66 degrees F too cold?

I use a hi/lo recording thermometer, I got 62 degree readings fairly often before the furnace got turned on for the winter. This happened nightly for 2 weeks and did not cause any problems with the plants.

I have heard that a large cold/hot spread causes stretch in newly budding plants, no confirmation on how much or if it really happens.

I've heard of that stretching thing too but I can't confirm it. I know you always want to keep your temperature difference as low as possible. 66 isn't bad, temps in the 60's help purpling if your strain has that trait.

a friend of mine showed me his best grow and i asked how he did it.. he told me keep the room at 65. as long as your lighting is adequate and your nutrients are right for your plant, temps in the 60s should be optimum from what I hear. However im looking to find out what different stages of life require different temperatures..or what they feel best in as a seedlings or in veg or flower..

...I'm runing a little experiment...not by choice but some of preflowering ladies had to withstand temps as low as 35 *F...They are finally moving in tomorrow and going on 12/12...finished the room tonight, I'll keep you guys posted on how they will do...

Some strains can deal with low temps better than others. most have no problem going into the 60's. I've seen outdoor sativas acclimated to my area that are fine all the way down to the low 30's.

Originally Posted by Phaeton

I have heard that a large cold/hot spread causes stretch in newly budding plants, no confirmation on how much or if it really happens.

I noticed a correlation between extreme temp fluctuation and stretching. I used 3 bagseeds, all of which came from the same bag. (Luckily, all ended up being females). All three girls started off indoors, but a problem with root aphids forced me to take precautionary action move one outside. They also switched to 12/12 on the same day. My indoor temps are 76/73 high/low, and outdoors its significantly lower, in the low 40s and high 30s (yes I know, I know.. but everything's growing fine and I'm prepared for a herm).

The two girls inside my tent have not stretched all that much, no more than doubling height after the first 2 weeks of flower. The outside girl stretched almost 2 1/2 times it's height within the first two weeks.

Same nutes, same regimen, same soil, only difference is the one that's being abused by the cold stretched a lot more.

No you are fine, on a side note if you have any purple strains the leaves will turn purple with low temps.

Your temps are okay, but common sense leads me to believe that if your plant is acclimated for a higher temp range, then it might have some problems when it gets colder.

If you see purpling, that's a sign of a Phosphorus deficiency, but cold weather makes it hard for Phosphorus to be absorbed by the plant. The purpling will be much more pronounced by the new growth if you have a P deficiency/lockout from cold weather.

Some strains, however, do turn purple naturally on stipules, petioles, calyxes, pistils and/or purple striped stems