Questions on humidity/heat

Hi. What is the optimal Relative Humidity for both veg and flower?

I have some marginal rolling indicating heat or humidity stress, however, I am 99.99% sure it isn't heat. My light is 1 foot away from the canopy and the probe (in direct light at canopy level) is only 4-6 degrees above ambient, sitting at 74.

My plants did not have the problem until I added an oscillating fan as an attempt to lower temps even more, since I wasn't satisfied with what I had. The fan runs 24/7, and my relative humidity is 35-40%, averaging around 39%.

veging humidity could be higher but I wouldn't worry about it.

Thanks frmrboi. Could my fan being on for 24/7 cause the margin rolling? What else could cause this besides heat and humidity? It's only the leaf set closest to the light fixture.

Optimal humidity for vegging is roughly 55%....For flowering you want it somewhat dry between 35 and 45 % IMO....

If your flowering your ok with 39% humidity....

Sevenpipers said:

What else could cause this besides heat and humidity? .

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either your lights a bit too close or far less likely a magnesium deficiency.

frmrboi said:

either your lights a bit too close or far less likely a magnesium deficiency.

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I sure hope the light isn't too close... It's only a 150w hps. It could be an Mg deficiency, because I haven't given it any molasses or calmag and I use RO water. I did apply some half-crushed dolomite lime though. So I'll try an epsom salt foliar feeding and turning the fan off at night and see what that does.