VPD charts and vague explanation

Just gonna make this thread because I see a lot of single VPD charts being shared a little out of context. Using around a mid range one will surely get you close. But I’m gonna post 0°-5°F/0°-2.8°C leaf temperature cooler than environment charts. All six of them. To truly dial in your VPD you will need an infared thermometer to measure and average your leaf temperature. Subtract that from the temperature of your tent/room to find out which chart to use. So if the leaves are the same temperature as the room, you use the 0 chart. If the room is 83 and the leaf average is 79, now you need the 4 chart. Which can vary a good deal. If you want the PDF just go to the website in the corner of the charts and they will email it for free. I took ordered screen shots awhile back tho, so here they are. Followed by a better explanation.


Great post! Never thought about the leaf/room temp difference.


My own current balance is what made me think of it. Think I have it about all figured out going into grow two. Definitely won’t have mold/fungus problems this time. Lol. Just need a leaf measurement in flower tent right before or as the lights come on. These cold/high humidity nights… No AC to help the dehumidifier, can’t freeze out the house (central). 76°/47%currently works on all charts. Got the large dehumidifier moved out to the rest of the house where it’s 70 with the heat on. You can see where temp dropping very little while humidity going up very little. I’d have to slow air movement. Which is impossible during lights out when I can’t get to the clip on fan or measure the leaves. Lol. Guess this is what everyone means by dialing it in. Thankfully this is only a seasonal issue. 80s one week, freezing the next. Fun times.

When I first decided to try this hobby of growing, I researched the various forums.
Strains interested in trying, the usual stuff.
Then out of nowhere I seen what @Budz just posted and the video. It is amazing how plants act, on the scientific level.
That dim lux also will sell you some cool gadgets to help control all that. $$$

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I definitely like some of their ideas on the controller. Supposesly simulating sunrise and sunset on a 10/10 schedule is as equivalent to what it says. 20% faster, since for the plants a day is only 20 hours.

“The Maxi Controller can also work with asynchronous times, for example, 10 hours on and 10 hours off; this setting shortens the process by almost 20%! Sunrise and sunset can also be simulated.”

This will need to be looked into. I’ll just use a vfd type controller.

Don’t laugh but it’s what you do when your on second shift in grow room.
I can’t remember the site but I said, beats looking at a printed paper.
Good stuff @Budz

Reading all the stuff they have is just mind blowing. But I’m on a country redneck budget.
But I’ll try my best to stay in that range if possible. Just reading about the science of this hobby is crazy interesting. Now here is another don’t Laugh.


I don’t have much different. SF 2000 kit, couple small necessary add-ons like a clip on fan and dehumidifier. Then a 4x4 veg tent I just play around with a couple free lights while trying to decide what to do with it. Because it vegs plants just fine. I would need upgrades of everything in first kit to use it to flower. Will put it together one day. I mean it’s definitely a pain to get in and out of tho. Not sure I’d want to flower in it. Cycle of life photo. Next one going into flower, it’s clone and the last one chopped at the time.

Doesn’t have to be fancy.

It’s so interesting to see and learn so we can improve. But that chart I really try to follow

Nice. That chopped plant in my last picture was my entry.

Nice!! I know I’m new, just my 5th grow but i think we got a shot at that winner spot one day

Wow, thanks for pointing out the leaf/ room temp diff.

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