How hot is too hot?

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Groat21

Active Member
Hey guys, I usually run my grow tent at 75F and I’m having a hard time keeping it under 77 and even 78 sometimes.

It’s a 3x3x6 foot tent, have a 4” exhaust fan running at full right now. It’s in my basement, which is around 65-72 degrees, more like a constant 70+ right now. There are two LED lights totaling just over 400 true watts, and an oscillating fan over the canopy. Oh and 4 plants in there as well, pretty well trimmed(once at flip, once 3 weeks in).

What I’m wondering is, how hot is too hot? I’m about 4 and a half weeks into flower.
 
Axion42

Axion42

Well-Known Member
My veg room is currently at 84-86 all day, I think leaf temps are more important which stay around 78-79 for me under LEDs.
 
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DaFreak

Well-Known Member
I've been forced to grow in extreme heat in the past in the high 90s. not ideal by any means but still worked.
 
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growingforfun

Well-Known Member
Groat21 said:
Hey guys, I usually run my grow tent at 75F and I’m having a hard time keeping it under 77 and even 78 sometimes.

It’s a 3x3x6 foot tent, have a 4” exhaust fan running at full right now. It’s in my basement, which is around 65-72 degrees, more like a constant 70+ right now. There are two LED lights totaling just over 400 true watts, and an oscillating fan over the canopy. Oh and 4 plants in there as well, pretty well trimmed(once at flip, once 3 weeks in).

What I’m wondering is, how hot is too hot? I’m about 4 and a half weeks into flower.
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Your fine to mid 80s.
It's also fine to have roses into the mid 90s if it's no more than a day or 2 at a time then dips. If heat goes up to the 90's I just reduce light for a couple days an let things settle down then turn the lights back up and repeat.
 
G

Groat21

Active Member
1212ham said:
That's strange, leaf temps are normally about 1C under air temp with LED.
http://www.just4growers.com/stream/temperature-humidity-and-c02/vapor-pressure-deficit-the-hidden-force-on-your-plants.aspx

To the OP, what lights do you have? Low to mid 80's is ideal under LED.... they don't have any IR to raise leaf temps higher than air temp.
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Thank you for this, the chart is outstanding! My temp gun is broken apparently, so I will have to get a new one to check on my leaf-air temperature difference. Never even knew that was a thing lol
 
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