I use a VPD calculator on my phone. It has a tab for leaf temp input, but I just use the default.Yeah man. I’m know I’m maybe playing with fire. I’m a little gun shy as I scorched a couple plants a while back top dressing too much too early. But these are almost day 30, so will probably need to happen sometime real soon. I might do a 1/4 amount and repeat after a week.
I’m trying to keep somewhat close to recommended VPD. Those charts you subtract a couple degrees for leaf temp vs ambient temp, right?
Just scroll down for the app links
VPD Calculator
Use our tool to calculate the Vapor Pressure Deficit (VPD) for your Cannabis Grow Room.
vpdcalculator.com