Wow. I’ve only become aware of VPD in the last couple days, but now I’m doing a ton of reading! This might be what has been causing issues with my grows all winter.
In winter, our RH% drops so low it’s like growing in the desert.
My current Temp/RH settings are causing my VPD to be way off into the danger zones and, some of the photos I’ve seen, of plants looking very sick due to severe VPD imbalance… look just like most of my plants have been all winter. I’ve been chasing down pH and Nutrient issues since last autumn. But… now I’m thinking it’s been VPD all along.
I’m adding code into my automation system, to auto calculate the VPD and add it to the graphs, so I can keep adjusting things until I get into the 0.8 - 1.0 range (Since this morning, I’ve already tweaked it down from 1.6 to 1.2, so its getting closer)