VPD goal

[Bud man 43]

Is the vpd chart referring to lights on periods or overall average?

 

[SofaKingHigh_]

Is the vpd chart referring to lights on periods or overall average?

You read a VPD chart by looking at where your grow room's relative humidity intersects with your grow room's air temperature.

This shows you whether the VPD in your grow room is in the sweet spot (if it is, great job, by the way!) Or if your VPD falls on either side of that ideal range. So it’s not just for lights on or off. Humidity swings are bad. Humidity is directly correlated to temperature so when the lights go out the temp drops and the humidity goes up.