The Grow Awards 2026 🏆 
humidity control
ATLien415answered grow question 21d ago
It is a continuous function, the acceptable parameters for temp and RH. Most folks go off VPD but ignore the infinite combinations to get said VPD. in other words, the chart 9/10 folks refer to is just a subsection snapshot of a much larger chart. Anyway, the pressure gradients in the air are much less important than the pressure gradients for your medium. As long as you aren't massively pulling water from your plants, then you really just need to make sure she is breathing okay...which is basically where VPD comes in. Just play around with it. Science go brr and math is fun.
00110001001001111Oanswered grow question 22d ago
Yup, temp and RH should be controlled together with a target VPD or avoiding extreme VPD high or low depending on how much control you have... Do what you gotta do to get there.
As long as there's enough gas exchange that you don't reduce resulting atmospheric CO2 around the leaves, adjusting intake/exhaust is definitely a valid option.
Buy a humidifier with a wick. Get some bacteriostatic solution to extend lifetime of the wick. Humidifiers are cheap to run but the wicks add up quickly. Regular cleaning can extend their lifetime a lot. The humidifiers that don't use a wick tha tproduce that visible vapor are the ones that coat everything in nasty, dusty film. you don't want that on something you smoke later.
As the plants grow, they'll add more moisture and that will help. If you choose to grow in a season with low RH, buy a humidifier. There's really no other way to fix it.
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m0useanswered grow question 22d ago
RH of 40-43 is not bad.
Use VPD Chat to see your position on it. 60% might be a bit to high and could lead to dew point and other issues at night time. but options are available to boost the RH. Mostly a humidifier in the room it pulls the air into the tent from.
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