Not to sound up my own ass, but i think i again am speaking casually and not specific enough. I'm answering to op basically and even mimicking his language in the first post. I'm seeing a new grower save that chart. Build it up to himself. Buying a humidifier and starting to mess with his girls chasing a chart he doesn't understand. I believe vpd is a major driving force in plants. I don't believe we know enough about it or plants or cannabis to say if it's relevant in an indoor garden situation. It's not something i would spend money on remedying or back it like it's proven science. Now, i don't use my anecdotal as real truth, but i couldn't get rh to do anything to a cut ive grown and harvested for 8 years, unless i started changing it during flower and that wasn't even visible, it just had "worse" sap tests.