VPD vs Rh and temp

Im on my second grow still learning and have a question on Vpd vs RH and temp. What would you guys say takes priority getting the temp and Rh right for the current growing stage or follow the Vpd chats? Im currently on week 5.5 and want to make sure im growing in an optimal environment.
Thanks in advance.


Temp and RH is my vote and good air circulation and exhaust :love_you_gesture:


Sometimes plants just have to adapt to the local conditions. Will it make a difference? Maybe. Maybe not. That will kinda depend on the plants tolerance.

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@elementhc I agree with :point_up_2::point_up_2:. Your plants look great, stick to what your doing cuz it’s working lol!!

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welcome to the neighborhood :grinning:

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@elementhc, Looking good! What strains are you doing?
I am a couple days from harvest on my third grow since starting in November. I have been using this chart for a year or so now.

During the first two grows during bloom I was able to stay on the dryer of the yellow scale. This was simply due to cold and dry weather. On this last grow it has been on the wetter side of the yellow, and sometimes bumping into the green scale.
The first two grows with the higher VPD definitely seemed to have a stronger smell than this last grow. The buds look just as frosty, and are maybe larger this grow. Same two strains BB and BW.
With that said, I don’t think it would be worth the trouble for me to try and stay on an exact temperature / rh point. As a salesman that I used to work with said.
“The juice is not worth the squeeze.”
Also I have found taking temperature or humidity readings from the wrong locations can send you down a rabbit hole. I like to hang my meter from a chain, and drop it down into the shadows of the plants. You can see the chain in the right side of this picture.


@Ickey they look good!! I’m digging the chain held gauge/meter-like a bikers wallet lol

Im running GG4, Bruce Banner, GSC, Ethos mandarin cookies V2, Ethos Booberry cookies.

The reason for my original question was that I dont really have a problem getting my grow room to the exact VPD or perfect temp and RH thats why I wanted to choose the best option for the plants. Currently at 75-77 degrees and 50% rh and the VPD is 1.47 which according to the chart is to high right?

@Fieldofdreams, Thanks, here is the BW it is doing better than the BB first picture. The BB had nutrient issues during the first weeks of bloom, and never made the huge buds like normal.

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@Ickey yo that thing is super badazz! She looks perfect. You got skillz bro!!

@elementhc, It appears that anything above 1.6 is too high.

@elementhc, On my first grow I had read that during flowering you need to be at 35 to 45 rh. So I ran out and bought a large dehumidifier, and was putting less than 40 percent rh into my tent while it was at 79 degrees. This was way off the chart, and somewhere around 1.9. But the plants showed no negative effects from it though.

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So according to that I cant follow the 77 degree and 45% rh because then the VPD would be way off?

77 @ 45 percent by my chart is 1.55, and is still in the yellow, and should be great.

@elementhc, Looks like you are into technology. Is that a phone app that you are using? Does this connect to a controller? If so where does it get the temperature and rh measurements from? Just asking looks like you have it dialed in pretty well. That is quite the variety of strains you have going.

This is what I use, it has sensor that is hanging in the middle of the tent.