VPD: The Final Stages Of Life

[OGeMann]

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Lets talk about VPD in flower, Am I supposed to follow VPD when in flower. humidity 30-40% temps 70-75F will give me a VPD of 1.5-1.65 {leaf temps -2,-3 cooler} that would be on the high end. do I keep the temp/RH or try to follow VPD. {just in flower}


what about if running CO2, and I am not, the last 2 wks before harvesting the RH should be between 40-30% 30% for the last week the VPD is at the high end of 1.6 When in that stage its at the right set of VPD just on the high or above set #.....currently I am at 74 F- 37%RH and that gives me a VPD 1.5 in witch I am at a 1.57
I have some pics WWA's at 85 days from seed

 

[YYCannabis]

Personally, i follow VPD guidelines more than following general humidity guidelines.

 

[gbauto]

What I've found is that typically the plants are less stressed when I can adhere to the suggested vpd for each growth stage,
When the vpd gets above 1.5, I get signs of stress of the top fan leaves.
I think this is from the plant attempting to transpire enough moisture through the leaves that they get overwhelmed.
The only reason I would intentionally run it that high is if the colas are susceptible to rot/pm.

 

[RetiredGuy]

I am at the same stage as you. I have seen that Nebula recommended a max of 73 f during late flowering, so have pegged my temperature there. My humidity is running 40% so that puts me in a good place for VPD. Earlier in the grow I was running as high a temperature as possible as long as the VPD was in recommended range.

 

[OGeMann]

that where I am at as of now 73F 40%RH...I used to fight humidity and it was a hard battle so I got to the point why fight humidity and just go with it. especially after you water/feed them so I just adjust temps to match the RH. Less stress for and a lot for me..