Leaf surface temps and co2

[Sprayo1e]

I was wondering what the ideal leaf surface temps were while running co2. I’ve read that your leaf surface temps should never exceed the ambient temperature but does this still apply running co2??

 

[Aqua Man]

I was wondering what the ideal leaf surface temps were while running co2. I’ve read that your leaf surface temps should never exceed the ambient temperature but does this still apply running co2??

So ideal leaf surface temps are about 75F. Increasing Co2 providing you have the light source (over 1000PPFD) will increase growth rates but also reduces the amount of heat stress and stress from low humidity to an extent.

 

[Sprayo1e]

I’m hitting about 80 to 84. I don’t own a par meter so I wouldn’t know my ppfd. I have a 315 cmh that been in a few runs with the lamp so I keep it about 24 inches away. I’ve thought about raising it to lower the temps but I feel like I would sacrifice the lights efficiency and what little it has left on it. Thanks for the reply. The ladies seem to be thriving and healthy so maybe I shouldn’t fix something that isn’t broke. Orrr invest in a par meter????

 

[Sprayo1e]

/ broken.

 

[Aqua Man]

Air temps or leaf temps? Increasing the air flow will help reduce leaf temps

 

[Sprayo1e]

80-84 are leaf temps. I have two oscillating fans and a clip on fan. I’ll move them where they’re both hovering just above the canopy to see if it helps. I run my duct fan but on the lowest setting to somewhat keep in the co2. If not then I’m just going to leave it as is. My first grow so I wasn’t really expecting a huge yield or anything. Pineapple upside down cake too which I heard doesn’t really have a big yield to begin with.

 

[Aqua Man]

80-84 are leaf temps. I have two oscillating fans and a clip on fan. I’ll move them where they’re both hovering just above the canopy to see if it helps. I run my duct fan but on the lowest setting to somewhat keep in the co2. If not then I’m just going to leave it as is. My first grow so I wasn’t really expecting a huge yield or anything. Pineapple upside down cake too which I heard doesn’t really have a big yield to begin with.

That and lowering the air temps should help

 

[Sprayo1e]

Word. Thanks for the advice

 

[DistyDemon]

I run 85* flip to week 5 (1400ppm co2)
Weeks 5-7 I drop temps to 82* (1400ppm co2)
Weeks 7-9.5 I drop temps to 78* (900ppm)

 

[Sprayo1e]

Can you please explain why and how exactly you drop those temps? Air flow or raising of the lights or....?

 

[DistyDemon]

How I change my sealed room environment? With my master greenhouse controller. I dictate what goes on in my grown rooms.

I change the environment to suit my grow style. Dialed in! The tricks you learn from a long time growing.

 

[Aqua Man]

Can you please explain why and how exactly you drop those temps? Air flow or raising of the lights or....?

So there are different ways to lower your leaf temps.

You can increase evaporative cooling by increase the airflow around the leaf. Just like people sweating and the wind blowing by cools you.

Raising the lights can reduced the radiant heat as well as the intensity of IR spectrum that increases leaf temps.

Lowering the ambient room temp with something like an AC unit will also lower the leaf temps. With say HID lighting there is usually more IR given off that warms the leafs so very generally speak leaf temps will be about 2f cooler than the air temps. In contrast LED generally lacks IR and leaf temps may be as much as 5-7 and seen some ppl report as high as 10f lower.

This is all based on a combination of forced evaporation amount of IR and ambient room temp. So as you can see there are several ways to address the issue of high or low leaf temps

 

[Sprayo1e]

I think I’ll just turn up some of my fans. I don’t have a completely sealed room so if I turn up my exhaust fan then ill lose too much co2. My ambient temps never get above 89. There’s no signs of heat stress I just hope the leaf temps being that high doesn’t mess with bud production.i mean if it was outdoors they’d be higher than that so I probably shouldn’t sweat it too much. Thanks again guys for the help. oh and I’m somewhat dialed in using an autopilot cobtroller