I only ever had mold once. The room RH was under 50%. Only one freak nod that was just too big and dense to grow. It was F1 Colombian x Afghan that had been in flower almost 90 days and was as big round as a softball.and hard as a rock and still had a long way to go.i follow the old advice of 75-77 farenheight max and 45-60% humidity and have never had a problem related to humidity.
It has long been proven that humidity is something the plant adjusts too and does not affect growth or yield.
Vpd is being mis marketed in my opinion. It is merely a guideline for greenhouses to manage humidity to the ambient temp. A band aid so to speak. There is no science that proves a specific atmospheric pressure for all leaf transpiration. Thats actually silly with plants thriving all over the world.
Indoors we have control so we do not need to compromise.
I am aware this opinion will start an argument. ;-)
I agree low humidity is just as bad as high humidity for causing mold issues and the worste conditions are high and low fluctuations.I only ever had mold once. The room RH was under 50%. Only one freak nod that was just too big and dense to grow. It was F1 Colombian x Afghan that had been in flower almost 90 days and was as big round as a softball.and hard as a rock and still had a long way to go.
I only ever had mold once. The room RH was under 50%. Only one freak nod that was just too big and dense to grow. It was F1 Colombian x Afghan that had been in flower almost 90 days and was as big round as a softball.and hard as a rock and still had a long way to go.
These have only been grown in high low Most days its 90% then drops to like 40%. But you know thats why im spraying them daily. So left to its own devices worst thing. I did have mold issues before i defoliated. I had left it au natural and that was the issue. Cause i had no air flow in the canopy. that was when i started flower it popped its head. Good 50% trim back and has been fine with the sprays. :fingers crossed:I agree low humidity is just as bad as high humidity for causing mold issues and the worste conditions are high and low fluctuations.
I agree low humidity is just as bad as high humidity for causing mold issues and the worste conditions are high and low fluctuations.
As was said good airflow. And I agree with @MIMedGrower these are guidelines.
BUT!!!! To many people use it wrong and that leads to the dreaded issues you hear about.
YOU MUST TAKE LEAFS TEMPS INTO ACCOUNT.
Will leave this here.
VPD (vapor pressure deficit)
Ok i was gonna sit down and write out a whole article but i have been lazy so instead instead I'm going to copy paste because im lazy. This is not my work so let start. You may find this very long but its worth the read. Some may want to skip ahead. I have added here and there to what i feel is...www.thcfarmer.com
Yes. That because RH is relative to temps. As the temos drop the humidity spikes. I would say #1 cause is light go out and humidity spikes and boom we have ideal conditions for germination of mold and fungus. Lights go back on RH drops and ppl keep it to low and boom we have ideal conditions for spores... rinse and repeat we have a massive infection in no time.Temp fluctuations while humid would be the biggest danger. Going cooler while room is too wet.
Most horticulturist agree a KPA of 1.0 is a good place for majority of plants not from extreme regions. Cannabis falls in there. Sure 50% is fine and nothing wrong with it. We are just talking about fine tuning here. Also VPD IMO is most impact full in medias that provide the fastest growth such as hydro or aeroponics. But its still good practice even if its not a must.I know you are a huge fan of this technique but it still doesnt make any sense. Who decided what conditions are optimal for the specific plant?
Just like high and low light plants. Tropical and mountain plants. Or any different plant they all have different light requirements, nutrient requirements and environmental preferences. Our plant has evolved to grow most anywhere.
And if it was really important i think the university of utah cannabis lab would be recommending it. They do not. They recommend keeping humidity indoors around 50%.
But you see with a humidity of 50% that is a recommendation that involves VPD even if not used by name. In our temps that many of us use this is acceptable range but that doesn't make it the ideal range necessarily for all stages if growth. Much like VPD is a guideline because some plants like the lower end of the recommendation and some like the higher end. Its not a one size fits all but much like a more detailed guidelines of say your 50% recommendation is all.I know you are a huge fan of this technique but it still doesnt make any sense. Who decided what conditions are optimal for the specific plant?
Just like high and low light plants. Tropical and mountain plants. Or any different plant they all have different light requirements, nutrient requirements and environmental preferences. Our plant has evolved to grow most anywhere.
And if it was really important i think the university of utah cannabis lab would be recommending it. They do not. They recommend keeping humidity indoors around 50%.
Most horticulturist agree a KPA of 1.0 is a good place for majority of plants not from extreme regions. Cannabis falls in there. Sure 50% is fine and nothing wrong with it. We are just talking about fine tuning here. Also VPD IMO is most impact full in medias that provide the fastest growth such as hydro or aeroponics. But its still good practice even if its not a must.
Sure ill dig some up when I get home. Lots out there.Do you have a link to a test proving your assertion? Because most growers are more worried about too high humidity. And even back in ed rosenthals book and others he tested a wide range of humidity and saw no difference in yield or quality.
But you see with a humidity of 50% that is a recommendation that involves VPD even if not used by name. In our temps that many of us use this is acceptable range but that doesn't make it the ideal range necessarily for all stages if growth. Much like VPD is a guideline because some plants like the lower end of the recommendation and some like the higher end. Its not a one size fits all but much like a more detailed guidelines of say your 50% recommendation is all.
Sure ill dig some up when I get home. Lots out there.
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