Vpd Survey

[crimsonecho]

great video for peeps new to the term. Very understandable for the average laymen. :D

Made me understand better :D

 

[greencraft]

What a great read I think I'm going to stay away from the vpd chart and go with the K.I.S.S method .
Keep my temps in the mid 70's, R.H. between 40 and 50 % for consistent results quality and yield .

 

[3 balls]

Amazon man just showed up! I'm gonna set the new humidifier at 60% and the de-hue's at 55%, wish me luck.

 

[Dbznthmman]

I run an average of 80 degrees and 70% humidity daytime, right around a 10.1-10.6 I believe.

 

[Dbznthmman]

I run an average of 80 degrees and 70% humidity daytime, right around a 10.1-10.6 I believe.

Side note--- I do run LED

 

[DETtoPDX]

I’ve seen enormous benefits in my growth speed since raising temps, adding co2, and sticking to the VPD. I only see a necessity to drop humidity in night time during flowering. Even then 55-60% is close to the optimal range of 68 degrees. I usually am at 65% rh at 81F during flowering, with no issues at all. There seems to be a discconect between the typical reccomendation of super low humidity during flower, probably mostly born out of stoner’s fear of bud rot.

 

[3 balls]

@1diesel1 could @Glow link it here please?

 

[1diesel1]

@1diesel1 could @Glow link it here please?

It would be more appropriate here.

 

[Glow]

It would be more appropriate here.

Thanks Diesel. Here's the link. It's a pretty simple overview of RH versus VPD but drops in a couple of important points for growers to understand.

 

[Rootbound]

Thanks Diesel. Here's the link. It's a pretty simple overview of RH versus VPD but drops in a couple of important points for growers to understand.

Nice link. Hopefully this makes it allot easier for newer growers to understand.

 

[3 balls]

Nice link. Hopefully this makes it allot easier for newer growers to understand.

Did you check out the grow info page on there? All kinds of cool stuff.

 

[Glow]

Nice link. Hopefully this makes it allot easier for newer growers to understand.

Thanks. I hope it helps. I try to decipher complex material/theory into layman's terms. VPD is a bit misunderstood by many growers which is why I put together that article. It's become a bit of catch cry lately and the danger is that many growers don't necessarily get that optimum plant health needs to be considered with some flexibility, factoring in other variables beyond temperature and humidity optimums. So for example don't run optimum VPD from about mid flower onwards because then humidity is at levels which promote PM, Botrytis, A. flavus etc. Compromises sometimes need to be made to ensure the best outcomes and getting the balance right is key.

 

[Ina]

Can i ask for your personal experience with a sweet spot? Do you keep at a certain rh? Anecdotal evidence? I have no intentions to answer to it or anything, genuinely interested.

My place was dry(and not really big,i'm no pro),never had PM or something,mostly problems with dryness so I know dryness really well:)Also it was hot ,about 29,30 C usually because of the bulbs and central heating in the winter.Hard to have moisture in the air with all these vents and stuff....I started to stretch the laundry there and it was getting dry in two hours!:)And i've noticed the difference when it is 30% and 50% by my own eyes,what better evidence(for me).Than I had that moisture meter for terrariums that comfirmed what I was already thinking. it was divided into four parts- red(absolutely dry),yellow-still too dry,green-nice(it was just between 50 and 60%)and blue for too much moisture.I've noticed that this also applies to plants. I saw how their leaves are getting greener and they look happier when I up the moisture to 50%.I think the sweet spot could vary ,for example: 60 for small plans and 45 for flowering but it is about 50 all the time....

 

[Monster762]

Thanks. I hope it helps. I try to decipher complex material/theory into layman's terms. VPD is a bit misunderstood by many growers which is why I put together that article. It's become a bit of catch cry lately and the danger is that many growers don't necessarily get that optimum plant health needs to be considered with some flexibility, factoring in other variables beyond temperature and humidity optimums. So for example don't run optimum VPD from about mid flower onwards because then humidity is at levels which promote PM, Botrytis, A. flavus etc. Compromises sometimes need to be made to ensure the best outcomes and getting the balance right is key.

Nice link I learned something from it. But kinda weird it told me not to follow vpd and explained why I shouldn’t.
And my grow kept going on like a lightbulb as I read it.
Idk I could be wrong but I’ve got a whole different lesson from it
And I might really be on to something. But don’t want to blow this whole thread up over it.

 

[Glow]

Nice link I learned something from it. But kinda weird it told me not to follow vpd and explained why I shouldn’t.
And my grow kept going on like a lightbulb as I read it.
Idk I could be wrong but I’ve got a whole different lesson from it
And I might really be on to something. But don’t want to blow this whole thread up over it.

I think you have misread what I am saying. The bottom line is understanding VPD is invaluable. Also certainly in environments with temperature fluctuations over the course of the day VPD is a great tool.

 

[Glow]

My place was dry(and not really big,i'm no pro),never had PM or something,mostly problems with dryness so I know dryness really well:)Also it was hot ,about 29,30 C usually because of the bulbs and central heating in the winter.Hard to have moisture in the air with all these vents and stuff....I started to stretch the laundry there and it was getting dry in two hours!:)And i've noticed the difference when it is 30% and 50% by my own eyes,what better evidence(for me).Than I had that moisture meter for terrariums that comfirmed what I was already thinking. it was divided into four parts- red(absolutely dry),yellow-still too dry,green-nice(it was just between 50 and 60%)and blue for too much moisture.I've noticed that this also applies to plants. I saw how their leaves are getting greener and they look happier when I up the moisture to 50%.I think the sweet spot could vary ,for example: 60 for small plans and 45 for flowering but it is about 50 all the time....

If you look at the VPD chart and correlate temperature to RH optimums it will give you a very good picture of RH optimums. During early Veg though you ideally want high humidity to help the plants settle in while they have smaller roots zones. Once the plants have settled though ideal RH is generally between 65 - 75%. As flowers begin getting larger though its wise to drop this back to help reduce the chances of PM etc.

 

[Glow]

Oh and should add though this is where understanding VPD is superb because it enables you to correlate temperature and RH optimum as a single value. Monsters point earlier that I was trying to say don't use VPD is actually off the mark. I may have worded things wrong for him or my statement might have been too vague. My point though is understanding VPD is great for indoor growers but you can pretty much establish that at this temperature optimum RH is this. My grow room temperature is always maintained at X (e.g. 82.4 F) and optimum RH (in VPD terms) is Y. So at 82.4 F using the VPD chart you can see optimum RH/VPD is between 70 - 85% RH. So once you have established optimum RH for your grow room temperature you strive to maintain RH in this range. That is if your lights on/day temps are maintained always at around 82.4 F and your RH is always maintained between 70 - 85% you are constantly running an ideal VPD. That is, as long as temperatures aren't fluctuating you ultimately are running ideal VPD if you maintain RH at between 70 - 85% at all times and you can pretty much at that point stop worrying about VPD and simply ensure your grow room temp and RH is constant by monitoring RH and Temp separately.

 

[Monster762]

I think you have misread what I am saying. The bottom line is understanding VPD is invaluable. Also certainly in environments with temperature fluctuations over the course of the day VPD is a great tool.

Nope pretty much that’s what I was saying was I’m outside vpd but have crazy uptake and output going on right now. I was under 40% til earlier it went up a little when I lowered temps.

 

[Glow]

Nope pretty much that’s what I was saying was I’m outside vpd but have crazy uptake and output going on right now. I was under 40% til earlier it went up a little when I lowered temps.

You'll find that trying to work in VPD optimums offers growth and plant health benefits. 40% RH is way too low unless you are in late flower and trying to prevent fungal pathogens. I hope I have clarified though that I'm a big fan of VPD. Its more a case that some growers misunderstand it a bit. The main thing really for less experienced growers to understand is that if you use the VPD chart it gives you a very good picture of where your RH should be relative to temp.

 

[Glow]

My place was dry(and not really big,i'm no pro),never had PM or something,mostly problems with dryness so I know dryness really well:)Also it was hot ,about 29,30 C usually because of the bulbs and central heating in the winter.Hard to have moisture in the air with all these vents and stuff....I started to stretch the laundry there and it was getting dry in two hours!:)And i've noticed the difference when it is 30% and 50% by my own eyes,what better evidence(for me).Than I had that moisture meter for terrariums that comfirmed what I was already thinking. it was divided into four parts- red(absolutely dry),yellow-still too dry,green-nice(it was just between 50 and 60%)and blue for too much moisture.I've noticed that this also applies to plants. I saw how their leaves are getting greener and they look happier when I up the moisture to 50%.I think the sweet spot could vary ,for example: 60 for small plans and 45 for flowering but it is about 50 all the time....

Humidifiers are very cheap and easy to run to increase RH.