How hot is to hot ?

Thc-ch-ef

Active Member
Rule of thumb.. if its too hot for you it's too hot for your plant. I seem to do fine with 28°c-31°c (about 85°f)
First 2 pics don’t seem to like
Last 3 are ok
Exhaust fan/carbon filter is on high, I have a 10” household occelating fan on med. but don’t know if should turn to high?. It’s pretty breezy in there now on med.
 

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shotnva777

Well-Known Member
First 2 pics don’t seem to like
Last 3 are ok
Exhaust fan/carbon filter is on high, I have a 10” household occelating fan on med. but don’t know if should turn to high?. It’s pretty breezy in there now on med.
Since other ppl keep resurrecting this thread, so will I! Looks good to me, but give them as much air (preferably fresh) as you can supply it. Your plants will never tell you to stop throwing air at them....

That said. I have a 200w LED grow light in my 2x4x5ft tent. I keep it high, because it gets HOT, but plants will eat it up.

I have my alarms set for anything under 65F and anything more than 92F for veg. As long as the 90 degree temps arent for more than a cpl hours of the day, they'll be fine. I go with 65-85F for flower. Controlling the tent temperature isn't too hard, as long as you have access to a window! It's fall now where I'm growing and with outdoor temps at 70-80F, my tent never breaks 92F with nothing more than a 6" inline duct fan pulling room temp air into it and a 6" inline duct/carbon filter venting to the outside. When it DOES get too hot, I have a 4" duct coming from the window, that I can hook to my 6" inline fan to (using a reducer), to pull in fresh, cold air from outside.
 

Tolerance Break

Well-Known Member
Since other ppl keep resurrecting this thread, so will I! Looks good to me, but give them as much air (preferably fresh) as you can supply it. Your plants will never tell you to stop throwing air at them....

That said. I have a 200w LED grow light in my 2x4x5ft tent. I keep it high, because it gets HOT, but plants will eat it up.

I have my alarms set for anything under 65F and anything more than 92F for veg. As long as the 90 degree temps arent for more than a cpl hours of the day, they'll be fine. I go with 65-85F for flower. Controlling the tent temperature isn't too hard, as long as you have access to a window! It's fall now where I'm growing and with outdoor temps at 70-80F, my tent never breaks 92F with nothing more than a 6" inline duct fan pulling room temp air into it and a 6" inline duct/carbon filter venting to the outside. When it DOES get too hot, I have a 4" duct coming from the window, that I can hook to my 6" inline fan to (using a reducer), to pull in fresh, cold air from outside.
Fuck it, ALL ABOARD THE NECRO TRAIN

I also go 65 to 85 in flower with humidity as high as 70 and as low as 45, optimally between 55 and 65 most of the grow.
 

dank'd

Well-Known Member
and now a word from the future... the year is 2020, where cannabis research is becoming more accepted as legalization continues

@8:58
 
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coreywebster

Well-Known Member
and now a word from the future... the year is 2020, where cannabis research is becoming more accepted as legalization continues

@8:58
Good video.

Is that under hps?
What I'd like to see on top of that information is leaf surface temp , to get an idea of radiant heat effects.
Similarly would like bugbee to look at that too.
Going off your discussion regarding led vs hps the other day.

Why?
Because all these guys are measuring air temp, rightly so.. however, the additional radiant heat I believe is what is causing that drop off in thc under HPS at air temps over 85f.
 
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Good video.

Is that under hps?
What I'd like to see on top of that information is leaf surface temp , to get an idea of radiant heat effects.
Similarly would like bugbee too look at that too.
Going off your discussion regarding led vs hps the other day.

Why?
Because all these guys are measuring air temp, rightly so.. however, the additional radiant heat I believe is what is causing that drop off in thc under HPS at air temps over 85f.
I thought people had caught up to the fact that increasing thc in a strain is lowering its quality. Guess the forums are still 40 years behind.
 

dank'd

Well-Known Member
Good video.

Is that under hps?
What I'd like to see on top of that information is leaf surface temp , to get an idea of radiant heat effects.
Similarly would like bugbee to look at that too.
Going off your discussion regarding led vs hps the other day.

Why?
Because all these guys are measuring air temp, rightly so.. however, the additional radiant heat I believe is what is causing that drop off in thc under HPS at air temps over 85f.
that is the question right there if under led the temps can be higher. i think those are hps btw. that is bugbee's lab also
 

GFZ420

Active Member
The plants which where grown in cold conditions (like 20C day / 16-17 night) where really hissing at me, when I put them in warmer place which reached 24C ambient and probably 26-27C leaf temperature.
Connecting humidifier for constant 60% RH to intake solved problem for me, plants stopped showing stress and continued to strech succesfully.
So I think it really depends on VPD (google vpd chart for cannabis)...
If you have everything above 26C run it at least 60% constantly with good air circulation. If you have cold conditions like with low watt leds (20-22) try to keep it at least 40-50 (50% ideal) and plant will thrive alright.
Also this is specific from strain to strain, because 1 hybrid (runtz x a.m.s) really hated high temps, but next to them very oldschool indica dom that was just fine...

High temps + low humidity = faster degrading THC, evaporating terpenes, airy buds
Low temps + high humidity = invitation for pathogens and overwatering, mould
Perfect humidity with perfect temp = perfect bud density, expressed terpene profile and of course juicy THC production
Find a balance.
 

coreywebster

Well-Known Member
that is the question right there if under led the temps can be higher. i think those are hps btw. that is bugbee's lab also
Aye this is it, I caught a bit of your other thread.
I do know there's a few in here running big operations, (or used to before the market collapsed) who switched to LED and did regular testing of the content ect and showed no loss at higher temps.

Personally I had issues years ago in veg when I switched to LED and the answer was to up my temps.

So when it comes to veg I just went back to MH and plants were happy.
In flower strangely had no issues around mid 70s but tend to be around high 70s low 80s .
But have had times in summer it's been 87f and not noticed a drop in quality. (Under LED)
However I'm in the UK and have no way to test it to know for sure, other than feedback from the usual suspects.
 

LeastExpectedGrower

Well-Known Member
Fuck it, ALL ABOARD THE NECRO TRAIN

I also go 65 to 85 in flower with humidity as high as 70 and as low as 45, optimally between 55 and 65 most of the grow.
These numbers work for me too, though I try to keep my low in the 74-76 range and the highs in the 83-86 range. I don't stress if they go up to the low 90's but that's rare unless I'm growing in the middle of summer, and I don't really do that anymore. Humidity I pin to VPD and try to keep it in the 1.3 to 1.7 range which generally has me in the 50's for RH.
 

Thundercat

Well-Known Member
People grow beautiful plants outside in California where it is regularly 90+ degrees most of the day and lots of the year. They rave about how potent and amazing their outdoor weed is.

My indoor grow used to max out at 83 in the summer with the way my ventilation was set up. Usually, it was high 70s lights on, high 60s lights off.
 

dank'd

Well-Known Member
an indoor tent with no ac in the summer is not 'outside in california' and is more like the danakil
 

Thundercat

Well-Known Member
an indoor tent with no ac in the summer is not 'outside in california' and is more like the danakil
Inside and outside are not exactly the same, but temps are temps. If you have airflow (thus co2 exchange) and the plants are watered properly then it really is pretty much the same. Cannabis plants grow perfectly fine at a range of temps, as long as they have the other things they need. Which just means making adjustments.

Its all about creating a balance for your plants to thrive in your environment, there isn't just one set of conditions that is perfect for everyone's grow space whether inside or out.

I'm in no way suggesting that anyone should make their grow room be 90 degrees all the time. The point was that if it happens sometimes its not a big deal, and if you have the other conditions controlled then the plants can still thrive.
 

dank'd

Well-Known Member
Inside and outside are not exactly the same, but temps are temps. If you have airflow (thus co2 exchange) and the plants are watered properly then it really is pretty much the same. Cannabis plants grow perfectly fine at a range of temps, as long as they have the other things they need. Which just means making adjustments.

Its all about creating a balance for your plants to thrive in your environment, there isn't just one set of conditions that is perfect for everyone's grow space whether inside or out.

I'm in no way suggesting that anyone should make their grow room be 90 degrees all the time. The point was that if it happens sometimes its not a big deal, and if you have the other conditions controlled then the plants can still thrive.
yes of course, vegetative growth is great in higher temps but flowering no. 83f indoors would be good for led but not hid 'for flowering'

i know first hand you can dial up the stink and the crystals indoors with high light and temps, while at the same time dialing the thc way down. same clone same season grown outdoors was mild and not really crystally but it actually got you nicely high
 

Thundercat

Well-Known Member
yes of course, vegetative growth is great in higher temps but flowering no. 83f indoors would be good for led but not hid 'for flowering'

i know first hand you can dial up the stink and the crystals indoors with high light and temps, while at the same time dialing the thc way down. same clone same season grown outdoors was mild and not really crystally but it actually got you nicely high
I ran 83 indoors under hps every summer for years and my weed was just as potent as it was the rest of the year. Same clones, same nutrients, same flower room with awesome results. 1000watt hps sitting 14 inchs above the plants.

You are putting way too much concern into those Youtube videos, bugsbee info, and anecdotal evidence. You are trying to compare a clone grown inside vs outside. All that proves is that specific plant prefers the conditions the outside grow had.

I've never given a clone to someone else to grow and had them produce anything close to the same quality that plant grew in my garden. I didn't assume those growers were bad growers, they just had different environments so the plants grew differently. It is literally the definition of "phenotype". Some plants will do better is certain climates and under certain conditions, others won't grow as well in those same conditions. That is another reason it's valuable to be able to adjust your grow conditions, and not just expect every plant to grow perfectly without any changes.
 

dank'd

Well-Known Member
I ran 83 indoors under hps every summer for years and my weed was just as potent as it was the rest of the year. Same clones, same nutrients, same flower room with awesome results. 1000watt hps sitting 14 inchs above the plants.

You are putting way too much concern into those Youtube videos, bugsbee info, and anecdotal evidence. You are trying to compare a clone grown inside vs outside. All that proves is that specific plant prefers the conditions the outside grow had.

I've never given a clone to someone else to grow and had them produce anything close to the same quality that plant grew in my garden. I didn't assume those growers were bad growers, they just had different environments so the plants grew differently. It is literally the definition of "phenotype". Some plants will do better is certain climates and under certain conditions, others won't grow as well in those same conditions. That is another reason it's valuable to be able to adjust your grow conditions, and not just expect every plant to grow perfectly without any changes.
the tent i ran was way hotter than that. plants grew super good in veg though. also, per chance you might also have the option of not timing a flowering period during the hottest time of year which is what i do here in canada

i think it was like four different strains in the tent, all went to shit. it was just ultra boiling hot in there. only the one plant had the outside clones but at those extreme temps with such a lack of fresh air there is no other explanation as to the extreme difference in the results

was really major informative also considering 9 out of 10 people would have chosen the tent headache clone weed over the (actually potent yet mild smelling) outdoor version because they looked so much crystally-er and had a deadly room destroying skunk odour
 

dank'd

Well-Known Member
so in that case, if all that is important is sick ass looking crystally knock out skunk reeeking buds then the non thc tent/oven version wins, when its cloned siblings grown same season same soil same pots outdoors are the actual quality grown actual thc having version they should be looking for

it would seem to be true then that, the same tent weed, grown with reasonable temps, would have the best of both worlds (crystals and funk and thc)
 

Thundercat

Well-Known Member
the tent i ran was way hotter than that. plants grew super good in veg though. also, per chance you might also have the option of not timing a flowering period during the hottest time of year which is what i do here in canada

i think it was like four different strains in the tent, all went to shit. it was just ultra boiling hot in there. only the one plant had the outside clones but at those extreme temps with such a lack of fresh air there is no other explanation as to the extreme difference in the results
Time your flower period for cooler times of the year is a great way to manage temps for some people. I was running a perpetual grow, so I had new plants going in every 2ish weeks, and I was harvesting every 2ish weeks. I flowered year round.

You said it your self why that tent grow failed so bad. It wasn't 83 in there, it was "way hotter then that" as you put it. You also pointed out the second major issue, "extreme temps with such a lack of fresh air".

It's all about the balance of growth conditions. You just make adjustments to make lots of things work in your space.
 

Thundercat

Well-Known Member
it would seem to be true then that, the same tent weed, grown with reasonable temps, would have the best of both worlds (crystals and funk and thc)
You are just making anecdotal assumptions.

Do some reading on what a phenotype is. The environment controls the genetic expression of the plant. Some plants like warmer temps some like cooler, some like more nutrients some like less, and the environment around the plants will change and impact those characteristics.

It really is not as simple as the same plant will be better in cooler conditions.
 
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