Day 8
Normally, I dont worry about relative humidity or VPD - other than to make a mental note that my humidity is to low and my VPD is too hi most of the time. For the most part, there isnt anything I can do about it other than lowering tent temps way down, so I pretend it isnt that important.
You would think that with the RH outside the house being in the 80%-90% range, that my tent would stay higher than 36%, but the temperature is very different. Its only in the 30’s-40’sF outside and I have been keeping the tent up around 80-83F.
I cant afford a real humidifier, and my few DIY attempts to force the RH up have been mostly useless.
It occurred to me when I first started HPA, that I have a source of hi humidity air in my root chamber. Its going to always be very close to 100% at around 70F. The problem with using that air is it would dry out the root chamber, and/or let light in, both of which would harm the roots. So I have not done that. My experiments with just leaving and opening between the chamber and tent did very little to change the RH in the tent.
The new seedlings are still in the perlite hempy’s, so I decided to try to raise the RH and lower the VPD in the tent again by blowing air down into one net pot hole and leaving the other two net pot holes uncovered while the nozzles run. That got me about 3-5% raise in RH. Then I lowered the temps from 80-83 down to 73-77. That made a bigger difference bumping the RH up another 10 points.
The combination of higher humidity and lower temps has improved the VPD a bunch. Its gone from being in the far red zone to almost in the green zone.
I was expecting/hoping that would keep the seedlings happier, but there is still almost zero signs of growth over the last 12 hours or so.
Im going to give them a bit longer then say screw it and put them in the chamber. I dont want to waste any more time.