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How hot is too hot?

  • by ohraesisstrakur
  • May 23 2010 09:05 PM
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  • (ow-rye-sis-straw-kur)

  • ohraesisstrakur
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Posted 23 May 2010 - 09:05 PM

So I've heard many varying things both on this forum and in books on the subject.
Some people think 80f is hot. The Cannabis Grow Bible says heat stress begins near 85f and that 75f is the optimum temperature, while I've also heard 84-86f is the optimum temp and plants can tolerate up to 90f fine. What are your opinions on the subject? How hot is too hot?
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  • (ow-rye-sis-straw-kur)

  • ohraesisstrakur
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Posted 23 May 2010 - 10:21 PM

35 views and no one has an opinion?

  • Snowy Buds

  • SmurfyBH
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Posted 23 May 2010 - 10:27 PM

Depends on the strain I say. I'd assume sativa's take better to heat than indica.

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  • GratefulFloyd
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Posted 23 May 2010 - 10:36 PM

I got 2 indicas and 1 sativa, My sativa is thriving with temp ranging from 78-95, One of the indicas is doing really well as well. The other one is having growth problems that may be attributed to heat stress or some sort of nute problem. I feel like plants can handle the high heat with other conditions being optimal ie Humidity, Nutes, pH. I feel like plants can handle the heat, especially since the can handle growing in outdoor environments such as India and the Middle East, which are just as hot.

  • (ow-rye-sis-straw-kur)

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Posted 23 May 2010 - 10:56 PM

Yeah I agree that it could be very strain depent. It was just baffling me that someone would say 80 or even 85 was too hot. These plants are native to India, Pakistan, Afghanistan, and so on. I know for a fact it gets a hell of alot hotter than 85 in those places. I also know I've grown outdoors thru 95f+ summers. Still if I see a 95 on my thermometer in my closet I might have a mini panic attack.

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  • Sam87
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Posted 23 May 2010 - 10:56 PM

Depends on the genetics. But generally, you want to stay below 85f to keep your buds nice and dense.

They can tolerate pretty much whatever on a short term basis. I had my fan go out once, box temp at 107, and they were happy as can be. But, if you're running Indica or Hybrid genetics, and are not running CO2, then around 75 is ideal. I shoot for 72, seems to be what my plants like best. But if you have to run at 80, it's not a big deal.

Also, outdoor plants are a bit different from indoor plants. They harden off quickly, and in ground their roots maintain a relatively stable temp. You have to remember that in containers, you're heating up that entire plant, and everything it takes in.

Edited by Sam87, 23 May 2010 - 10:59 PM.


  • (ow-rye-sis-straw-kur)

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Posted 23 May 2010 - 11:04 PM

That's true Sam, but I was growing in containers outside, they still made it just fine.

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  • Sam87
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Posted 23 May 2010 - 11:17 PM

A Cannabis plant will make it pretty much anywhere, definitely nicknamed weed for a reason. It's the matter of fine tuning for yields and quality that's such a bitch. But all in all, people put waaayyy too much work into their plants. Don't get me wrong, attention to detail is very important, but the way some people treat the subject, you'd think that the damned things wouldn't even make it past a seedling in nature.

The bitch part of everything to do with growing, is that there is no set model for perfection. You need to get everything dialed in with the genetics that you have, not with what Cervantes or Rosenthal or Green has, you know? If the plant works for you, then it works for you. But you can always play with it to see if you can make it work better.

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  • Makizushi
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Posted 23 May 2010 - 11:21 PM

Due to unchangeable circumstances, my grow tent is at 100 degrees when the light is on. Although the yield is smaller, I can still grow.

85 is too hot IMO
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  • Maggot sack

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Posted 24 May 2010 - 01:48 AM

Well what about plants outside that grow in 100+ temperature sometimes.

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  • Sam87
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Posted 24 May 2010 - 02:54 AM

They don't yield as well as in a controlled enviroment. Or, they have/are adapting to their enviroment. Same as anything else with plants, you have an optimum range, and a tolerated range, which can both differ by way of genetics and other enviromental factors.

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Posted 24 May 2010 - 03:02 AM

Both indicas and sativas can tolerate indoor temps into the high 90's if they are well watered and cared for. I regularly get temps in that range and still have good yields.

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Posted 24 May 2010 - 08:29 AM

My grow room normally sits around 100f or tad more but have had nice yields! my last grow was same as I'm doing 2 AK47 x Lowryder 2 (auto) and got just over 2 and half o'z dried per plant :)


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