What I been saying. People don't realize how important it is
I fully appreciate that VPD is one of (if not the most) important factor when growing. When I was using the AC infinity controller I would set it on humidity control at ~72% RH and high temp thresh at 84F... Thats pretty much right on par with what @Lanestrainley was suggesting which is about a VPD of 1. However, the limited material I've seen on VPD says higher VPD for flower. You seem to be suggesting using the same VPD in veg and flower. I haven't grow enough to actually argue that X is better than Y but as a data nerd, if you have any quantifiable way to show that lower VPD is better in flower I'd love to see it.
I agree in part but, at 30c you reach peak photosynthesis and the plant is actually using the uptake instead of storing it, and once you push it it’s stress, the smoothest tastiest buds doesn’t come from late choice feeding programs, it come from perfect vpd all the way through and boron at the right times in the right amounts, the plants actually racing at that point and if you’re already using Co2 you can only pump up the photosynthesis by introducing phytochromes. The plant uses the uptake and doesn’t store it, that’s why I can feed a 850ppm schedule and get the results I’m looking for. Flavour AND yield. It’s my personal so I want both. SST, LAB tea work wonders on low ppm feed schedules with proper vpd.
Naw I think lower humidity is ok.in later flower to prevent mold issues
this is something i've never herd of till reading this post .never learned this any where else ,more notes for grow log ,have to try this with the young ones ,as soon as flower plants finish.
how does one know what vpd your garden is @? they have a meter for that?
what is a good VPD controller ? not the highest priced , limited funds
I use a short cycle timer and a humidifier set to constant. Then I take a infrared thermometer and measure leaf temp, then I make the adjustments needed, if any. For the most part my attention to room design is what allows me to do this with such little gear. My room size/btu ratio is damn near perfect and the bulbs dry the air out almost perfectly, I need to run a dehuey in late flower though. There is a vpd chart available across the web, this works for most plants, I’ve found the sweet spot for cactus, avocados, lemon trees and a Nanking cherry tree, proper VPD helps with grafting immensely.
bad case of sticker shock for me,looks like the 4 gang wall plug goes to work! leaf temp @72f in my small abode53%rh,82 degrees f , seems i've got to swing a filter and do some other things
... plants say it's OK."
I got a cheapo lux meter but that was mainly to try and quantify what was working already than to try and optimize anything.
My guess is my VPD is probably 3 or higher. Less than 10% RH and 81 F right now in the closet. I think I'm pushing it.