What's your VPD chart?

Is that a cannabis VPD chart?

Yes it is

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I used it most of my grow

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Here’s a nifty chart that uses sliding bars to dial in VPD: VPD Chart


Oh heck, what are these values regulating? Just when i start to feel like im getting a handle on this concept new stuff hits me i havent learned about yet and this looks important. Lol i will have to dive into it, any links ya could pass my way that are good and reliable?

Ive been watching my humidity and temps according to what ive found but had no idea i needed to dial it in on this level… And they say potheads are idiots…

Appreciate this comment big time! 3 weeks into first grow and thought i was doing good on my temps and humidity until i started reading this post…had me researching and freaking out about learning yet another new thing. I just wanna get through a couple grows without killing em!

VPD is like DLI. If you keep your rh and temp in the standard recommended ranges you’ll find you’re at or very near the appropriate VPD.

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Basically, what this chart is telling you is what temp and humidity gives you maximum growth. The min and max are the ranges you want to keep your grow space at. If you can keep a plant in the perfect VPD (which can be difficult) then it’s going to grow at its best genetic rate.

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Thank you. Being a first time grower should i just do my best to keep them in the ranges everyone is suggesting and worry about this when i get more experiance behind me?

This is a maximum growth rate chart. Even experienced growers have a hard time maintaining the perfect VPD. Do what you can to get close and don’t stress about it if you’re out of range. Just make sure you’re humidity levels aren’t too high in flower.


I found that I needed to check if “ideal” air temp suggestions were for HID or LED, after seeing a wide range of ‘ideal’ air temp suggestions when I started with LEDs for the first time this grow & trying to look up some suggestions. I had a lot of headroom left in my leaf temps with my LEDs, but trying to run at cooler ideal HID air temps.

Personally I like to use the dynamic chart posted above at
vpdchart dot com
& also the VPD calculator at the dimlux website
because they both allow me to set my actual leaf temps into them after I record them with my temp gun, & then they tell me my Leaf VPD .

Personally I don’t like the static charts, because I found them too confusing due to the single leaf temperature offset that each one is good for. Too easy for me to just start looking at the wrong one, even when I know what my offset is & what chart I should be using for that offset.

Agreed. Plus using an IR thermometer is fun. It’s one of my favorite gadgets.


@BobbyDigital @Nubie419plus1 , I agree simple is better for the beginner. I think for most beginners, it is best to use the 40%-60% rule (close to 60% in veg & 40 in flower). For their first grow or two. This time is better spent learning other growing techniques like, waterings, feeding, trimming and lighting.
After this pick up one of the VPD charts and use it for a reference only at first, and see how far from optimum conditions you are running.
After learning what the chart is telling you, and tracking your conditions. You can make a much better decision about if it is worth trying to maintain optimal VPD, and what equipment you will need to maintain it.


That’s what seems to be key, at least in my situation

That’s where the mold starts to build inside your buds, when it’s over 55%+ humidity in flower.


@Ickey thank you for that explanation, I think I’m a ways from trying to dial in vpd
You’re right about getting the basics down first :+1:

Biggest problem in my life right now :sweat_smile:

VPD stands for Vapor Pressure Deficit. It is a way of measuring how much water the air around your plants can remove from them and how much water it can contain. It is related to humidity, which is how much water the air has.

Sometimes, growers only focus on the humidity of their growing space, and they think that is what makes their plants grow well. But VPD is more important because it affects how your plants give off water and absorb nutrients.

Please check out our VPD Chart, so you can make sure your plants have the best growing environment.

Leaf temperature - Air temperature = Leaf temperature Offset.

Pick the proper VPD chart by matching your Leaf Temperature Offset to the Leaf Temperature Offset used to generate the chart.