KarateChopMaster
Active Member
Growing autoflower at 18/6. Should I be keeping the humidity the same during the dark time as I do for light?
Dark time humidity?
- Thread starter KarateChopMaster
- Start date
King Avitas
Well-Known Member
60-65% when lights are on, 40-45% while lights are off.
Those are just a basic set of numbers that will keep you fairly safe.
Myself I try to maintain my rooms VPD (Vapor pressure deficit) around 1kPa. So at 90⁰f, I run about 74% humidity while lights are on but then during lights off, I drop down to 40-44% humidity.
Those are just a basic set of numbers that will keep you fairly safe.
Myself I try to maintain my rooms VPD (Vapor pressure deficit) around 1kPa. So at 90⁰f, I run about 74% humidity while lights are on but then during lights off, I drop down to 40-44% humidity.
Milky Weed
Well-Known Member
Wow thats warm! Maybe i should try to let my humidity rise during the day, i went to 90 a few times with 50% humidity and the plants werent happy lol.
King Avitas
Well-Known Member
I am running a pretty aggressive set up. CO², Quest dehumidifier, AC, sealed room. Keeping the VPD at 1KPa in conjunction with the CO² has allowed me to run these higher temps and honestly with the LED lights, I need the temps up there to get the most out of the CO² that I am adding to the rooms environment.
calvin.m16
Well-Known Member
Why 1.0 kPa? I'm pushing as high as 1.6 kPa with the same type setup except I'm running 1000w DE HPS. If your running a high CO2 wouldn't you want a higher VPD to account for the increased photosynthesis and metabolism of the plants?
King Avitas
Well-Known Member
1.6 is too dry for this guy.
Raising the VPD to high levels cause the plant to transpire more that it wants to and if this continues for long periods of time the stomata start to close off as a defense mechanism to prevent high transpiration rates from continuing and the plant from losing its moisture. This closing of the stomata can reduce CO² uptake and ultimately slow down transpiration and nutrient usage while causing the plant to stress out.
Many ppl think making your plant transpire lots will make them uptake and inturn use more water/nutrients but Infact it does the opposite. It slows down everything because the CO² uptake is lowered from the closing stomata and that reduces photosynthesis and the reduction of photosynthesis causes a reduction in the production of glucose that the plant feeds on. It is a fine balancing act.
Currently I am in veg so 0.9 to 1kPa is fine for me but in flower I will go up to 1.2-1.4kPa. I will also drastically reduce my temps to preserve terpene profiles.
All this said, I am not a biologist or an expert in anything scientific. But this it just what I have learned from reading lots of shit online. I hope I interpreted it correctly, I may have missed something but I am pretty sure this is the basics of why I run my VPD where I do.
DrOgkush
Well-Known Member
I’m running 86-88F ambient. 70-81 lst
With a humidity of 70-77%. I’m usually around ..6-.7 kPa. My entire grow changed to a forest in 3 weeks. It really steers your garden in veg with more shoots and tops. Or bud sites rather. Prepares well for flower. And helps with overfed plants a lot. Essp with those whom have issue sprouting seeds. This is the way to go. Made the biggest difference in my garden indoors. But I know for a fact you can’t get away with very low humidity.
From what iv learned. High kpa will hinder your plants breathing.
With a humidity of 70-77%. I’m usually around ..6-.7 kPa. My entire grow changed to a forest in 3 weeks. It really steers your garden in veg with more shoots and tops. Or bud sites rather. Prepares well for flower. And helps with overfed plants a lot. Essp with those whom have issue sprouting seeds. This is the way to go. Made the biggest difference in my garden indoors. But I know for a fact you can’t get away with very low humidity.
From what iv learned. High kpa will hinder your plants breathing.