Heat Wave ! Help

I grow with one 600whps in the garage. I am 40 days into flowering and there is a heat wave coming. It will be 105+ degrees for 8 days in a row. My 24,000 BTU AC can only get the temp down to 90 with the lights at 30 % power. Once the sun goes down at 9 or so my AC is able to battle back so my night temps have been 68, as I like cold night temps.
So the flowers will be in 90 degree temps for 5 hours a day, for a week or so.
IF I cant get the grow room temperature below 90 for that one week period of time, what will happen with the pants? So I guess Il find out , I have several pics and I will post more in a bit. All the plants are very healthy right now. The heat wave is going to hit in 2 days. I will post results. I am going to try and use Ice to battle the heat i.e. frozen gallon jugs in the tent.
How worried should I be? What kind of damage will there be?

Theyll slow down n foxtail and drink a shit ton of water, some strains can handle hot temps better than others

Yeah I'm going through the same problem can get to 115 here during the day now. Like said above all depends on the strain and genetics. I have had some that power right on through in 85-95 temps and others that felt the heat and were affected. I guess you will find out. IMO I would just put a couple fans on them to help at high speed.

you should just reverse your lighting dude i know you like cool nights but its best to run your lights at night rather than scorching them. id just leave my lights off till the next night then have them come on at like the time you want at night and go from there.

and a fan or 2 going....keep in mind plants grow outside it gets way hotter out there but they have wind. if it's 90 for 5 hours I think they'll be fine. I agree with zubey they will slow down.....but (and this is the newby in me asking)I wonder could you introduce co2 during that time and get a benefit? or is that more of vegetative thing? eh just throwing that out there
the plant will have some rebound time at night
just keep those fans going

mmmmbrownies said:

and a fan or 2 going....keep in mind plants grow outside it gets way hotter out there but they have wind. if it's 90 for 5 hours I think they'll be fine. I agree with zubey they will slow down.....but (and this is the newby in me asking)I wonder could you introduce co2 during that time and get a benefit? or is that more of vegetative thing? eh just throwing that out there
the plant will have some rebound time at night
just keep those fans going

Click to expand...

My understanding is that the CO2 will just increase temperatures. Much like it's causing a greenhouse effect with the planet, it'll do the same thing (hold in the heat) in a tent/closet/garage. I may be wrong, but that's my understanding.

As for heat in the 90s, it's not good, but the plants should survive. I'm often in the high 80s and low 90s for part of the day now, and I've noticed some slower growth, but not much else.

Cheers and happy growing!

you will need lots and lots of airflow like the others have said, if you have enough fresh air you should be ok

mrblu said:

you should just reverse your lighting dude i know you like cool nights but its best to run your lights at night rather than scorching them. id just leave my lights off till the next night then have them come on at like the time you want at night and go from there.

Click to expand...

Well I liked this idea so much I did it two grows ago. I ran my lights at night during the summer grow. What happen was my Ac could only keep the 'lights off ' temp down to 75-80 at the hottest times. Then when my lights came on at night, the AC could keep the room at the desired 78-80. It was a dissaster. the plants were stunted in growth and they NEVER finished flowering. I got a harsh lesson in THERMOPERIODISM. Now I make sure i get a 20 degree drop in my night temp. Day/night temp is crucial to the plants chronological clock along with light cycle In my newb opinion. My buds are fat and getting fatter and frosty. Hope they hold on through this heat wave... And i hope I dont get a repeat of last summers never ending flowering cycle. I will post more pics throught the heat wave and document.


and the obvious 'well you need a better AC comment is not needed, thanks ahead to any trolls.' actually even my giant AC on my house can only get the house down to 79 -80 when it hits 106 . valley gets hot

Impman said:

Well I liked this idea so much I did it two grows ago. I ran my lights at night during the summer grow. What happen was my Ac could only keep the 'lights off ' temp down to 75-80 at the hottest times. Then when my lights came on at night, the AC could keep the room at the desired 78-80. It was a dissaster. the plants were stunted in growth and they NEVER finished flowering. I got a harsh lesson in THERMOPERIODISM. Now I make sure i get a 20 degree drop in my night temp. Day/night temp is crucial to the plants chronological clock along with light cycle In my newb opinion. My buds are fat and getting fatter and frosty. Hope they hold on through this heat wave... And i hope I dont get a repeat of last summers never ending flowering cycle. I will post more pics throught the heat wave and document.


and the obvious 'well you need a better AC comment is not needed, thanks ahead to any trolls.' actually even my giant AC on my house can only get the house down to 79 -80 when it hits 106 . valley gets hot

Click to expand...

Marijuana plants can easily thrive without temperature fluctuation between lights on and off, its unnecessary to have a large drop in temps for the dark cycle. Almost everyone runs their lights at night.

For the heatwave,whenever I have to deal with heat..I feed them with a more diluted lower ppm strength. When it is really hot the plants will transpire water faster,but not use up the nutrients at the same high rate. So if it is gonna be hot for a while, watering at high ppms can lead to nutrient toxicity/salt build up.

As to the co2 mentioned - cannabis generally tends to halt growth above 80°. Adding co2 lets them continue to thrive to upwards of 95°, so there's this benefit of adding it. I think the other concern here, and it might be more important, is to monitor soil temperature and do your best to not let it get out of hand. Ideally, you want your soil to stay as close to 70-75° as you can, as a healthy root system is your best defense when battling excessive heat. We constantly are subjected to 100-110° temps in Nor-Cal and I use a fast draining soil that pretty much makes it impossible to over-water. As a result of this we can water as needed at a temperature that will keep the soil temp within reason. In between watering we sometimes spread a couple cups of ice cubes over our mulch and just let them melt and trickle down through the soil. A little misting on the foliage with a breeze from a fan will help keep the canopy temps down - just be careful since you're flowering and don't ever let the misting bead up anywhere. You want just enough to cool without accumulation. A light mist can drop canopy temps considerably.

Since your in flower.....you need to run the lights during the cool time (night) and during the hot time (Day) run the AC and no lights

If you try to flower AND your night time or dark period is above 85-90... you wont grow buds ...youll grow hairy airy shit

BustinScales510 said:

Marijuana plants can easily thrive without temperature fluctuation between lights on and off, its unnecessary to have a large drop in temps for the dark cycle. Almost everyone runs their lights at night.

For the heatwave,whenever I have to deal with heat..I feed them with a more diluted lower ppm strength. When it is really hot the plants will transpire water faster,but not use up the nutrients at the same high rate. So if it is gonna be hot for a while, watering at high ppms can lead to nutrient toxicity/salt build up.

Click to expand...

I see you did not read about thermoperiodism. It is very important to have day/ night temp fluctuations. I dont think you grow anything.

Well I'm in tx, 12 months without a measurable amount of rainfall. 90 days over 100 degrees.
My grow stays at 78 so maybe get a better attitude along with an ac

qwizoking said:

Well I'm in tx, 12 months without a measurable amount of rainfall. 90 days over 100 degrees.
My grow stays at 78 so maybe get a better attitude along with an ac

Click to expand...

sure thing Tex.

What are you doubting? Google will prove the weather and my thermometer says 78... or were you in fact agreeing to the change of attitude