Vpd Survey

[crimsonecho]

That article shows to use the chart to vary the conditions based on goals.

For our purpose we would want high humidity for clones for example and much lower for flowering to avoid mold and pm.

The chart is just another way to see parameters. Also helps to avoid reaching dew point.

It is being misused by the weed forums like gas-lighting or any number of agriculture techniques turned into weed growing myth.

Ok i mean vpd is a tool that people can use i’m just saying that. There is evidence that keeping it in a sweet spot works. Maybe we don’t know what works for cannabis specifically, in kpas. But i would think people know they should temper with vpd at different stages.

 

[MIMedGrower]

I get what you’re saying about vpd being just a measuring tool. Its the difference between what air can potentially hold and what its currently able to hold at a given temperature if i get that correctly.
Now growers can use this info to keep the vpd at sweet spot.

I disagree. It is very misleading to new growers who should be learning to manage high humidity. Better to understand it is showing how close the relative humidity is to the dew point.

Following that chart in an indoor grow room is a quick way to mold if the humidity gets away from you.

 

[MIMedGrower]

Ok i mean vpd is a tool that people can use i’m just saying that. There is evidence that keeping it in a sweet spot works. Maybe we don’t know what works for cannabis specifically, in kpas. But i would think people know they should temper with vpd at different stages.

On all the weed forums new growers are trying to follow the chart religiously as if it is a magic set of parameters to stick to.

And it excuses what I believe to be too high humidity for a grow room.

 

[crimsonecho]

I disagree. It is very misleading to new growers who should be learning to manage high humidity. Better to understand it is showing how close the relative humidity is to the dew point.

Following that chart in an indoor grow room is a quick way to mold if the humidity gets away from you.

No no i get it just non american here, i can’t exactly put it into words :)
I dont think following a 70% rh in an indoor situation will give you mold. I have 70% most of the time no mold. Just tiny bits of pm only if i splash water onto my leafs. Better watering practices.

 

[MIMedGrower]

No no i get it just non american here, i can’t exactly put it into words :)
I dont think following a 70% rh in an indoor situation will give you mold. I have 70% most of the time no mold. Just tiny bits of pm only if i splash water onto my leafs. Better watering practices.

Tiny bits of pm..........



Mold spores become active at 60% relative humidity and above. Proper air flow is key and can stop it from taking hold but spores are everywhere. I take the safe route.

I run 2 70 pint dehumidifiers here to keep the house and grow under 60%.

And I run a humidifier too for keeping it above 40%.

 

[crimsonecho]

On all the weed forums new growers are trying to follow the chart religiously as if it is a magic set of parameters to stick to.

And it excuses what I believe to be too high humidity for a grow room.

I get you about this much humidity not being ideal for some stages of growing but it does not negate the fact that the paper you shared also includes a very obvious sweet spot for tomatoes. Now i’m sure there is one for cannabis too. Whether this chart fully expresses that or not is up for debate but this does not negate the fact that there is a sweet spot based on vpd. This does not mean that it should be kept in the same kpa all the way thru. Your study suggests the same. But that would be a personal choice. You can keep it as high as you like to get more frost but that doesn’t mean the plant is healthier. The heightened production of resin due to environmental stress is actually a manupulation technique to stress the plant which would make it less healthy. The definition of health is important i think.

 

[crimsonecho]

Tiny bits of pm..........



Mold spores become active at 60% relative humidity and above. Proper air flow is key and can stop it from taking hold but spores are everywhere. I take the safe route.

I run 2 70 pint dehumidifiers here to keep the house and grow under 60%.

And I run a humidifier too for keeping it above 40%.

Yeah like the size of a timble maybe.
Thats not a big deal. On one or two leaves, just pluck it.
If the rh was the sole culprit in this scenario i should have gotten a broader problem. Not on some leaves that i splashed water or dripped my sweat :)

 

[MIMedGrower]

I get you about this much humidity not being ideal for some stages of growing but it does not negate the fact that the paper you shared also includes a very obvious sweet spot for tomatoes. Now i’m sure there is one for cannabis too. Whether this chart fully expresses that or not is up for debate but this does not negate the fact that there is a sweet spot based on vpd. This does not mean that it should be kept in the same kpa all the way thru. Your study suggests the same. But that would be a personal choice. You can keep it as high as you like to get more frost but that doesn’t mean the plant is healthier. The heightened production of resin due to environmental stress is actually a manupulation technique to stress the plant which would make it less healthy. The definition of health is important i think.

Another myth. Ed rosenthal tested all parameters extensively many years ago. Humidity was not found to influence flower quality.

But it sure can influence mold.

 

[MIMedGrower]

Yeah like the size of a timble maybe.
Thats not a big deal. On one or two leaves, just pluck it.
If the rh was the sole culprit in this scenario i should have gotten a broader problem. Not on some leaves that i splashed water or dripped my sweat :)

It means you are pushing the limits. It is on more than the leaves you can see. Any pm visible is an alert to a big problem.

I highly suggest you lower your humidity.

 

[Daikokuten]

Another myth. Ed rosenthal tested all parameters extensively many years ago. Humidity was not found to influence flower quality.

But it sure can influence mold.

Do you know offhand if those tests are in one of his common books? Sorry to ask you to do work.

 

[MIMedGrower]

Do you know offhand if those tests are in one of his common books? Sorry to ask you to do work.

Yes. His main grow book. And there are links to free pdf’s online. I don’t have one in my new phone. Sorry.

Also light spectrum testing including proving uvb influences thc. And information on temperature for different wattage and pretty much every other thing argued on the forums.

 

[crimsonecho]

Another myth. Ed rosenthal tested all parameters extensively many years ago. Humidity was not found to influence flower quality.

But it sure can influence mold.

Well i can not say anthing on that i havent seen the paper but i think lowering rh will cause resin production. Don’t know what you mean by flower quality. The probable resin production would be stress induced in this case. Stress that will mess with plant functions. I’m just saying people do that to get more resin and i think it should work (because its a plant response) but that doesn’t necessarily means better flowers.
I think saying rh has nothing to do with flower quality is a little unorthodox and it doesn’t make sense to me. Would love to see a paper on that. I mean plants coexist with the atmosphere and respond to changes.

 

[JWM2]

Ok I quit growing ;-)

 

[Daikokuten]

Yes. His main grow book. And there are links to free pdf’s online. I don’t have one in my new phone. Sorry.

Also light spectrum testing including proving uvb influences thc. And information on temperature for different wattage and pretty much every other thing argued on the forums.

I recognize the spectrum stuff from my readthrough, but i can't recall these tests. I lend my books out constantly, which is actually why i asked. Know who to text for coffee tonight with that book
Edit: forgot to say thank you. Appreciate it.

 

[crimsonecho]

It means you are pushing the limits. It is on more than the leaves you can see. Any pm visible is an alert to a big problem.

I highly suggest you lower your humidity.

Ok there isn’t a problem with pm. I know these spots are caused by drops of sweat and nute water and i mean 1-2 spots and this is not a common occurence for me either. Would it be better to go 60%? Yeah but its impossible to get rid of spores as you know and a drop of sweat or nute water can still let them grow. So no worries on my side. And to be honest i think using this much electricity to grow plants is kinda fucked already.

 

[MIMedGrower]

Ok there isn’t a problem with pm. I know these spots are caused by sweat dripping and nute water and i mean 1-2 spots. Wouldn’t it be better to go 60%? Yeah but its impossible to get rid of spores as you know and a drop of sweat or nute water can still let them grow. So no worries on my side. And to be honest i think using this much electricity to grow plants is kinda fucked already.

And there it is. The ultimate motivating factor. Money!

Amazing how much personal agenda is involved in arguments.

And lowering humidity does not increase potency.

And more trichomes also doesn’t mean more potency. What’s in them does.

Lot of confirmation bias in these discussions.

 

[1diesel1]

you guys are scaring the youngsters!

 

[MIMedGrower]

you guys are scaring the youngsters!

I worship 30 days of Halloween. ;-)

 

[crimsonecho]

And there it is. The ultimate motivating factor. Money!

Amazing how much personal agenda is involved in arguments.

And lowering humidity does not increase potency.

And more trichomes also doesn’t mean more potency. What’s in them does.

Lot of confirmation bias in these discussions.

First of all its not money, its the fucking planet.
Secondly thats what i’m talking about. I’m not saying it increases potency. Not saying more trichomes means more potency. I’m just saying it causes heightened resin production. This is due to environmental stress. So you cannot expect a stressed out plant to produce better. You may see more trichomes but without a lab test it doesn’t mean shit. So keeping a healthy vpd should get you better results in the end.

 

[Daikokuten]

you guys are scaring the youngsters!

The main message here is an important one for them. Don't get caught up in conversation and mind your sources. You have to build your own way of scrutinizing information and i would hope this thread would inspire them to keep it simple and research basic plant science. Might just be me that gets that though.