Let's talk temperature, can we?

[FinestKind]

Hey again everyone, happy new year! May this decade be at least a little more progressive than the last, hmm?

So, when someone says "the ideal temperatures for flowering when enriching with CO2 are 80 to 85 degrees", does this mean the temperatures at the canopy? Root level? Ambient room temperature? Because with my brandy-new aircooled sealed room, I can keep the glass on my hoods about 5 inches from the tops of the plants (for a stationary 600) and it stays at just about 84 degrees at the very top of the canopy... however, the room temp never gets too much above the low 70's, which means the roots are probably somewhere in this range, if not lower. So, what are the temperatures that matter most? I know you don't want to overheat your canopy, but I'm not sure the low 70's ambient is ideal, either... thoughts on this one? I've been wondering about this for years now, so please go into lots of specifics and details... thanks! Oh, and feel free to ask about the details of my setup that matter, because I'm too tired to have thought that part of my question out too much.

FK

 

[phatboyfromla]

I'm wondering the same thing. Never really grown when it's been this cold outside and now I've had to add a space heater just to keep the ambient temp around 70 during lights off. I also keep a meat thermometer stuck in one of the pots so I can see what the root zone temp is and it seems to stay around 70 during lights on and 60 during lights off. My plants really seem stunted although they're starting to pick up.

 

[FinestKind]

Can anyone help us out here? My room gets down to around 66 at night, I still have one 600W HPS to fire up as soon as my clones are ready to go under, which should help out some.

 

[Bunz]

You want to measure your temp at the canopy level. In nature, the ground will stay much colder then the air temp. Therefore the root zone is always at least 10 degrees below the canopy level.

I've had my garden get down to 55 at night with no ill effects. In fact, lower dark temps during flower will encourage the plant to have purple hues to it.

Bunz

 

[Balance]

I grew in a place that was susceptible to outside temp changes. 55 - 50 degrees F was about as low as they could take without noticeably stunting. Once or twice prolly doesnt matter, but if you hit those low temps all grow you may want a 'lil heat. Your buds will definately purple at those temps, too.

 

[draco]

there is some information here:

http://www.icmag.com/ic/showthread.php?p=2964346#post2964346

 

[mpd]

85F is the room ambient we seek. Above that and plants will grow at a slightly faster rate, but some varieties may hermie. You can grow them down to the mid-60s, but they take a while to finish and the yield suffers. By and large, I have found that growing at around 80F to 90F means the grow will proceed at a good clip and if you are growing in soil you will need to be watering every other day to every second day depending upon your soil mix. If it is straight coir it is definitely every other day.

Be safe and grow the same way.

 

[FinestKind]

85F is the room ambient we seek. Above that and plants will grow at a slightly faster rate, but some varieties may hermie. You can grow them down to the mid-60s, but they take a while to finish and the yield suffers. By and large, I have found that growing at around 80F to 90F means the grow will proceed at a good clip and if you are growing in soil you will need to be watering every other day to every second day depending upon your soil mix. If it is straight coir it is definitely every other day.

Be safe and grow the same way.

Okay, so if we're looking for 85 ambient, what is an acceptable canopy temp? And "ambient" seems a bit vague, too... ambient where? Away from the lights? Far corner of the room?

I just know that temperature means something very specific in weather... it's 3 feet (or 1m) above ground level in the shade... there has to be something similar for our purposes, no? I mean, where should I stick my thermometer for "ideal temps of 80 to 85"... this is of course open for debate, too, it's just what I've gathered from various opinions on the subject from various places.

Again, thanks for the input everyone!

FK