VPD/Humidity – Bud Rot/PM

[rama777]

Yo! I have my flowering tent between 55-60% humidity in mid-late flowering. I could lower it more with the dehumidifier but that comes with a cost of course. So instead I keep the 6” exhaust on 9, and the 6” intake at 8, and this in a 3×3, plus two oscillating fans. TONS of airflow so I’m not worried about anything right now.

But, the fans are noisy and I’d like to turn them down if possible. The temps in the tent during lights on are 77-78 degrees. During lights off it’s between 72-78.

However, when the temps are on the low side, the humidity is down to about 50% so regardless, my VPD is always above 1.3

Assuming my VPD is hovering at 1.3-1.6, is it overkill to have the intake and exhaust cranked up so high?

[chr is]

I think your daytime RH might be ok. Especial considering the flowers are being warmed up from the radiate heat from the light and photon energy flux?

AT night we all should be concerned with this time. When the lights turn off the RH raises rapidly and stay high till the light comes on. Big Plants breath a lot and evaporate a lot water, mold and mildew up at night. Constant air flow air circulation is required, or a dehumidifier (this cost money)

Wow VPD I’m not a good guy for this. MY VPD on my enclosed porch rises to 3.5> into the 4’s very high. Good air flow and giving the plant an endless amount of water(RDWC) with nutrients has worked for me. Or very frequent watering in an ebb and flow hydroponic system.

Otherwise with my high VPD’s, my plants would die in soil or I would need a giant pot to make up for the VPD VS ROOT SURFACE AREA that gets me by.

[chr is]

I’m just a grower trying to help others out. I don’t want to pass on any bad info to you.

[chr is]

OH MY high VPD are because I have a enclosed porch sun room. I have 2 16″ temp controlled vents each set to open at different temps with an AC infinity 16″ shutter fan controlled, controlling all of it AC infinity PRO69. Very good reliable automation, AWESOME. 12’x24′ height 8ft

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