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Im getting ready to put my girls in flower tomorrow. As of now in veg my room is 50 to 55 percent at about 76 degrees. What is to high of humidity? Also I know 78 is perfect temp from what I read in flower. Will it affect it much if it was like 82 83 with light of then about 70 with lights off?

Edited by williams2311
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  • 2 months later...

Jorge Cervantes lists those parameters in his book, free online. Your temps and humidity is fine. There is no perfect temp. Think about nature?

If you can keep your humidity from rising, mj likes cooler temps at lights off, but beware.


It rains outside, with 100% humidity, and marijuana grows fine, when resources are available. As the season ends though, these resources dwindle, and plants will succumb to mold and disease. Unhealthy rooms produce unhealthy plants.  I followed his advice when having my rooms constructed, and have never had one issue with any of the plagues I read about here. I do not try to be thrifty in the grow rooms, because my patients' health is important to me, and them.


If augmenting with c02 a higher temp is fine. I've seen marijuana thriving in a greenhouse at 113f, but they had every available resource needed, so no worries. If your room is dialed in with perfect parameters, small changes to temps and humidity are no worries. hope this helps

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I keep my garden around 70-75* and 35-45% humidity in bloom, and no higher than 80* & 50% humidity, with PLENTY of airflow, which is essential to preventing mold and fungal diseases and also helps strengthen the stems. Anything LOWER than that increases your risk for gnats and pests to thrive, which we also DO NOT want to contribute to. Ya can't live here, guys, so don't even try! The lights i use are 100W HPS. I keep the lights cooled and at least 12" above the tops of the flowers. 

Higher humidity is dangerous for mold and fungal issues. So keep the air moving and don't get too warm. This is appealing to may new growers because it is said that higher humidity in flower means for higher trichome production (which DOES NOT MEAN more potent buds). I suggest the higher humidity in the beginning of bloom (maybe within the first couple weeks, but not too much longer than that). Keeping the humidity on the lower end of the scale, allows for the plants to uptake nutrients and water more quickly. This is important if you are on a feeding schedule that calls for FEEDING twice a week with essential watering in between. That way, you can get them their correct food doses without risking over-watering.

I keep the VEG room a little higher; between 70-80* and 60-70% humidity at the most. ALSO with plenty of airflow. My veggies look amazing. Healthy, big, bushy, green, beauties. I keep the lights around 4-6" inches above the tops of the plants. Too close can burn, too far can cause unnecessary early stretching. 


The main reason for these climates, is that I like to keep a "safe zone" in the tents. I have read that you can get your temp down to 60* up to 80*; and down to 30% and up to 60% humidity IN BLOOM, but, that is the very bottom & very top ends of the scale and then anything beyond that is "pushing the envelope". Which i tend to try and avoid when it comes to my girls. I would rather be safe than sorry with them, and in turn, keep my stress levels down and my patients as happy as they have been with the final product.


I have some amazing reviews on my flowers, both growing AND cured, Hopefully this information helps someone get the same results!!


BEGINNER GROWERS: You must remember that these are just guidelines. Don't press your luck. Find what works best by messing around with the temps and humidity  (within reason, no more than a 10* swing at a time). Also remember, you will find your perfect comfort zone for growing in optimal conditions. You will not be perfect the first time around, so DO NOT get discouraged, and stay motivated, and keep up the good work. This is no cake walk, despite what others may have you believe. It is a intricate job. It requires PATIENCE, lots of ATTENTION, and a willingness to learn, bend and grow.. :) Keep an open mind. Stay positive! 




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