Vpd Latest Research Contradicts 30-40% In Flowering Rh?

[alkymisten]

Hello guys. Completing my first grow and getting more and more confused by more and more reading ..

Seems like old saying is 30-40% RH but VPD completely contradicts this.

Can you say VPD is latest research and the low RH recommended on a lot of sites is just old news and granddaddy advice with no real science behind it?

Seems like when mine are running at 28-29 with lights on I will have to run at 75-80 RH to achieve optimal RH for indica @ 8 VPD and lights off 23-25c 70-75 RH.

Seems like you would need lab-like clinical sterileness here to avoid mold etc which is supposed to thrive at 60-65 RH and also be able to completely control air in/out and a crazy AC.

Whats the truth?

 

[RooR5mm]

Your enviros are variety dependent. Never have had a problem following VPD chart ever with any variety. Typically my RH is 15 to max 20 points below temp.

 

[redlife215]

When i used to grow indoor i statred out with the mindset of low humidity to lrevent mold and stuff but the more i saw jackmayoffer/jungleboys grows i was more tempted to try to run at tge proper rh. High temps high humidity and co2 made my room grow at an amazingly new faster pace. Nothing that i have ever done or used made such a noticable difference in tge plants growth. Anything jackmayoffer does or says i take as fact as shluld any other grower.

 

[redlife215]

I always used co2 by tge way, but in conjunction with 80 plus temps and high humidity the plants blow up

 

[RooR5mm]

At 25c 60% is safe. You can go higher but it is variety dependent. When the flowers start stacking depending on the variety you could see rot.

 

[alkymisten]

At 25c 60% is safe. You can go higher but it is variety dependent. When the flowers start stacking depending on the variety you could see rot.

Safe as correlated to the VPD chart?

So would 65-70 RH be safe in 27-29 range also correlated to the chart?

Worried about diseases now I’m that far.. I did discover black surface mold in windows before

 

[RooR5mm]

60-65 at a min yes. I never go to the high end of the VDP only to play it safe. In veg yes but in flower I’m weary.

 

[RooR5mm]

Right now I’m at 75f @60%

Edit. I just raised my ac this weekend from 72, I should probably add 5% more humidity. I didn’t adjust dehue. They have a cpl of week’s left.

 

[alkymisten]

Alright. Lastly everyone says jungle boys I did follow the instagram but I’m not seeing a lot of advice more bud pics, girls etc ;) not that its not very nice but you know what I’m after.. If you have any modern growers who shares research or any sites, magazines, etc. I already follow maxyield, bigbuds, hightimes.. I will search for that username jackmayoffer here to suck in some info- but would really love some resources to follow to get the latest and greatest advice

 

[RooR5mm]

The black mold is because you need to add some more insulation and really seal off that space better. Condensation, cold outside with a hot moist room.

 

[redlife215]

Alright. Lastly everyone says jungle boys I did follow the instagram but I’m not seeing a lot of advice more bud pics, girls etc ;) not that its not very nice but you know what I’m after.. If you have any modern growers who shares research or any sites, magazines, etc. I already follow maxyield, bigbuds, hightimes.. I will search for that username jackmayoffer here to suck in some info- but would really love some resources to follow to get the latest and greatest advice

I dont know about the ig account i am referring mainly to when he was on tge forums as jackmayoffer.

 

[CaliRooted]

30-40% is too dry regardless if u follow VPD or not

 

[dirkdaddy]

Just imagine what the average climate is like. Unless your growing in the mountains your RH will rarely stay at 20 or 30 for very long. That's nosebleed type air. Tropical plants like hot, humid climates. I think bud rot is more of a function of the fact that we all strive to attain massive, seed free nugs which invite rot and mold. But the way the plant grows and the type of climate it prefers doesn't change, regardless of how much human tinkering there has been to try and create big, juicy buds.

 

[GT21]

 

[Ignignokt]

VPD is essentially a measure the ability of air to absorb moisture at a specific temperature with a specific ambient humidity level. It is related to, but not equivalent to humidity level. The one thing you don't want is condensation on the leaves and flowers - so VPD is a guide to keeping the humidity/temperature combination in balance to prevent condensation that leads to mold and mildew. The other thing to remember is that VPD is measured at the leaf surface, not somewhere else in the enclosure. If you measure temperatures at the leaf surface, they tend to run somewhat higher from the red spectrum present in almost all light sources ( LED growers know YMMV if their lights are not particularly hot in the red spectrum ). To get leaf temps for evaluation of actual VPD, you can use a non-contact type thermometer when the lights are on.

We have had some pretty good if not slightly heated discussions of VPD on this site. I can recall one with a grower in Colorado ( @Douglas.C ) where he makes a credible case for low humidity - but in his case the low humidity is free. In my case (I live ~20 miles from the coast) humidity control is damned expensive to duplicate the levels he sees in Colorado. My ambient humidity levels are usually ~50% on dry days so I tend to look for controlling the VPD number more actively. I design my own sensors and controllers to help manage the environment for variables like this.

When you add Co2 and get photosynthesis in high gear - a side effect is dumping significantly more moisture into the air as well as Oxygen ( For every oxygen molecule O2, one water molecule H2O ). So at the leaf surface - humidity levels get pretty high unless the VPD is also relatively high (high deficit). I've seen photos here of plants literally dripping water in this mode, like it was a good thing. I'm pretty sure it doesn't lead to the kind of product I want. Freaky for sure, but not a good thing.

 

[Ignignokt]

This is the remarkable difference between animals and plants. These are two solutions for life that our planet has implemented that happen to complement each other ( there are others ). We utilize each others waste in a marvelous closed cycle on a rock in space. It becomes pretty clear why water is key.

There is much more to how it works, however this is the basic mechanism that should be understood. The more you stimulate photosynthesis, more water that must transpired, regardless of nutrient concentrations in the plant water supply. With high nutrient levels and high transpiration, you will get nitrogen salts burn or other mobile nutrient toxicity since the water transports more nutrients than required, as a side effect.

 

[RippedTorn]

Wtf are you talking about.

You follow big buds magazine? Fucking Big Mikes guerilla marketing blog? You didn't notice these websites are nothing but advertisements?

Let's get to the root of the problem here fellers. Quit listening to book and nute sellers. Vpd isn't a thing.. You cant touch it or feel it. It's a range. As temp goes up so does humidity.. Common sense. The theory of Relativity or some shit..

No wonder its confusing to internet growers. It can't be packaged in a bottle of fucking sugar waterr potassium magnesium juice..

 

[DemonTrich]

FUCK AN and that bish ass phedophile Mike!

Now that that's out of the way.

I follow VDP from veg thru week 4 in flower only.

 

[alkymisten]

Wtf are you talking about.

You follow big buds magazine? Fucking Big Mikes guerilla marketing blog? You didn't notice these websites are nothing but advertisements?

Let's get to the root of the problem here fellers. Quit listening to book and nute sellers. Vpd isn't a thing.. You cant touch it or feel it. It's a range. As temp goes up so does humidity.. Common sense. The theory of Relativity or some shit..

No wonder its confusing to internet growers. It can't be packaged in a bottle of fucking sugar waterr potassium magnesium juice..

Not a single piece of advice or pointers in your post. Just ranting. Can you admit this please? First grow here. What do you expect? I’d love your advice but now ur just assuming.. Give me some real advice instead of humiliating a first grow.. It might not be medical lab quality but I’d say I take things a lot more seriously than other amateurs and willing to learn hence why I’m asking here..

 

[OGchemist]

Hello guys. Completing my first grow and getting more and more confused by more and more reading ..

Seems like old saying is 30-40% RH but VPD completely contradicts this.

Can you say VPD is latest research and the low RH recommended on a lot of sites is just old news and granddaddy advice with no real science behind it?

Seems like when mine are running at 28-29 with lights on I will have to run at 75-80 RH to achieve optimal RH for indica @ 8 VPD and lights off 23-25c 70-75 RH.

Seems like you would need lab-like clinical sterileness here to avoid mold etc which is supposed to thrive at 60-65 RH and also be able to completely control air in/out and a crazy AC.

Whats the truth?

I know not not everyone can afford super expensive dehum and UV light filters to kill bacteria and spores but that reap all you would need and you can find cheap decent ones just a though.