I think VPD is having a negative impact on new growers...
Lately ive seen new growers too reliant on VPD and they don't actually know what it is, or they are tuning their controllers to hit specific VPD because thats what they are told to do or thats what their controller defaults to
Aaaand I'm here to tell you that is not the full picture / or the best way to grow (imo)
Let's use 0.8 vpd as an example:
84F (air temp) with 80%rh is 0.8vpd and this is around what I would recommend for seedlings/early veg
57F (air temp) and 50% rh is also...0.8 vpd...would I recommend these temps and humidity for seedlings?
No, too damn cold. Sure the vpd is on point, but your plants would not grow well in these conditions...
Do you see the issue here?
Vpd isn't some magical number that gives you maximum growth, there's multiple different temps and humidity levels that will get you to the same vpd numbers...
Temps and humidity are very simple but we are complicating it with this shiny new vpd number!
Heres my advice, ditch VPD and follow the numbers below:
From seedling to late veg try to use 77-84F (air temps) and 70-80% rh
Then you can slowly decrease temps and humidity over time
I like to end up at around 73-77F and 40-60%rh for the rest of the grow/flowering stage
There's 3 main goals (regarding temp/rh) when growing:
Use high temps/humidity from sprout till late veg to get fast growth rates while the plant is focusing on roots
Use lower temps during flower so you dont ruin your terps
Use lower rh during flower to lower your chance of bud rot
Its really that simple, dont get caught up in the VPD hype and dont rely on some AI controller to do it for you!
This post is not for engagement farming and I did not use AI to write this, I just wanted to type it out because I think it will be a helpful reference for alot of people
Thanks for coming to my TED talk, the next lesson will be about PPFD cause I saw 5 people giving bad advice about ppfd within 10 minutes of waking up this morning 😅