76-78deg F. is perfect in a non-CO2 enriched atmosphere. If you are using supplemental CO2 of some kind (ppm above 1500 or so) plants can thrive in temps up to 93 or so. I run my room at about 91F. with my CO2 running about 1900ppm. getting great results.
That's fine for the strains of plants you're growing and other strains also, but there are strains that WILL NOT grow at temps over 88 F
Your buds look great Ryan!
above 75 farenheit the cannabis plants stomata begin to close, the enrichment is only compensating for the overheating. light beyond 5500 foot candles of photosynthetically active radiation bounces off the plant as heat
You guys are both right IMHO:
I've seen test grows in sealed rooms completely halt growth at 90 degrees with CO2 enrichment. They were commercial tests done by medical licensed growers hired by a nutrient company. The plants constricted, shrunk and died. They looked like a 120 year old person.
The test was done with different strains in different rooms.
The best advice for anyone growing in a non CO2 room is 74 to 78 F
In a room with CO2 you should not go over 85F unless you are prepared to carefully check and monitor the plants. Once a plant starts to die from CO2/heat poisoning it's hard and wasteful to try to get a good crop from them.
The best thing to do is grow several crops out at different temps and see what THAT strain likes the best. Just like nutrient levels, strains like different levels and temps which goes back to their blood line and where they originally come from.
that the cooler room produces frostier buds.
Give more sugar (carbs) to your hot room plants than you would to a lower temp grown plant; and still give them the sugar during your water only flush stage. They'll still put on sugar weight all the way to the chop