87 degrees temp

We are still having warm days probably until mid Oct. I noticed my grow room temp at 87 during heat of day. Am I stunting growth at that temp? At night it goes down to 72-76

With decent ventilation, shouldn't be too bad. What lite schedule are you running? Can you change your lights on time to run at night? From what I've read here a 10 degree swing from lites on and lites off is optimum. My high temps are about 82 and low 72 or so, fall is coming on here so I'll be breaking out the heater soon and off with the AC

Get that temp under control bub, some plants can take it but its dependant on many variables:
Genetics, Grow area size, C02 concentration, Rh, etc.
But generally, I'd keep it below 85.

Yes. You growth rate will be much slower than at 80 degrees. Unless you are running co2 you dont want your grow to go above 80 with the lights on. Also any more than a 10 degree difference between day and night stresses out the plants. Growth pretty much stops at 90-95 degrees in a fresh air room. Internodal spacing also increases causing airy buds. I have personally battled the heat inside my whole life. When its 100+ outside it gets expensive to cool a grow. Good luck! Keep em vertical!

I live in the desert so my humidity in grow room averages 35%. My grow is GDP, AK 48 and Cotton candy. Mostly GDP. They look great right now. My grow room is only 4'x 4.5' with only a 50" ceiling. I have a vortex 175 cfm fan that exchanges that small room at an acceptable rate. I have a 600watt MH in cooltube and phat filter, soil grow in 3g pots (fox Ocean forest with 25% perlite added. I have topped above second node.

My first grow was in AZ, now I'm in America's Heartland and the conditions are totally different. Where are you pulling your air into the room from? Is it possible to cool the intake air. Kinda like a lung room to pre condition the intake air. Sounds like your dialed in except for the temps

Almost every grow I've ever done the temp has been above 80. As long as you have good ventilation you're ok. Plus, the temperature the thermometer reads isn't 100% accurate. If you want an accurate reading of temperature get yourself an IR thermometer gun. Another thing... co2, almost every home has more co2 inside than outside so you don't really need to add co2.

Yes, well I have a venting system that services a "evaporative cooler". I have shut it down for season and pulled unit back to it lets outside air flow easy in vent system and mix with open vents on inside. I have a 8" vent poc opening in the grow room. It pulls air from that vent opening into grow room. I can feel a light flow coming through it when fan is on. The inside temp is 72 degrees in rest of house ( this is an attic grow) and the outside right now during day is 75-82 degrees on average. I have lights off from 12:30pm to 6:00pm. Usually when it comes on at 6 it heats up due to outside air and 600watt light. It starts dropping about 10 or so at night again. I think in a few more weeks I will be ok. Just do not want to stunt growth at 87 degrees which it hits for about 4 hours out of the 18 grow cycle. I need to get them into flower by first week of Oct. That is because I have limited vertical space and would like to harvest a couple weeks before the holidays.

mr2shim said:

Almost every grow I've ever done the temp has been above 80. As long as you have good ventilation you're ok. Plus, the temperature the thermometer reads isn't 100% accurate. If you want an accurate reading of temperature get yourself an IR thermometer gun. Another thing... co2, almost every home has more co2 inside than outside so you don't really need to add co2.

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IR guns are nice but they only read surface temps not ambient temps. i use one on my car to see how hot my turbo is getting but it isn't going to me the temps of my general garage area.

I dont think their is any problem with high 80's temps even low 90's at peak with good air flow. it is dead air that hurts the plants. You must be bring in fresh air from outside or running co2. I have grown large colas battling high temps but come through with big buds. What do you think the temps get in CA on outdoor grows. Temps are in the 100's. The plants obviously will require more attention to watering though. Also I do not believe it hurts plant growth to drop temps about 20 degrees to lights off period. That is natural. Again temp drop is more then that all the time on outside grows. Run your lights at night, I duct air from outside, so the cool night air in the Winter is the perfect ac.

Pop The Trunk said:

IR guns are nice but they only read surface temps not ambient temps. i use one on my car to see how hot my turbo is getting but it isn't going to me the temps of my general garage area.

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That is exactly my point. What is more important, the temp of the turbo or the temp around the turbo?

Pop The Trunk said:

IR guns are nice but they only read surface temps not ambient temps. i use one on my car to see how hot my turbo is getting but it isn't going to me the temps of my general garage area.

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That's why I use both, but I go mostly by surface temp. I've seen surface temps over 100° outside when I was doing the inside/outside shuffle. I don't know if those high temps outside slowed their growth but they were sure tracking the sun across the sky. Still, inside, where they are now for good, I like to keep 80 or under w/ good airflow.

Ideal temps indoors are 72-76. 10 degree drop at night will show no noticeable change in growth.