Yeah, no complaints At All
The middle back one is a cross between Maui Wowie and OG Kush, both of which are guesstimated to be 4 feet high plants...
All caught up Chuck. They are looking great! The uppotting really made them happyI understand pressure gradients, what and how VPD works. All plant bio chemistry functions on pressure gradients. My question was why is it, that the charts and calculators, have so much variation, from one to another. I know that there are different charts for different stages of growth. Plugging the same temp, RH and stage into several calculators or charts tends to yield different results. Calculators do seem to be far less accurate. This is just the first chart from a google search result. Notice they don't exactly match. 75F 60RH is a perfect VPD 1 on your veg chart but that would be a 1.19 on this chart. Perfect for late flower. Good science is repeatable. Why isn't this repeating?
.You don't insert leaf temp in place of ambient, you need a calculator that has 3 inputs. Room temp, leaf temp, and RH.Ah, so you can factor leaf temperature IN place of ambient !
Thay may explain the differences in charts...
But I am not buying another gadget
Cheers
Awesome. Thanks.Yeah, no complaints At All
The middle back one is a cross between Maui Wowie and OG Kush, both of which are guesstimated to be 4 feet high plants...
The lower right is the Acapulco Gold, a cross between Central American Genetics x a Mexican Sativa ! This one can be a five footer
Cheers
So looking forward to trying it
My SOP has always been to flip at around day 50 and with topping/training they are around 18" tall. Still, I've had runts that I ended up super cropping at 5'
I've always taken that as a ball part figure and go ahead and grow the strains I'm interested in anyway
As I mentioned I have limited control over my environment.All caught up Chuck. They are looking great! The uppotting really made them happy
Not to keep beating the VPD subject, but it is both powerful and dangerous if not applied correctly. This chart posted by @Sativa1970 isn't a plant VPD chart, it's a room VPD chart. 2 very different things.
@Chuckeye you mentioned
You don't insert leaf temp in place of ambient, you need a calculator that has 3 inputs. Room temp, leaf temp, and RH.
I use this one.
I got it from the Google Play Store.
If you have a VPD meter such as the Pulse meter you can't just assign something like a 2 degree offset into the settings and leave it that way.
You need to make note of your current room temp, then use an IR gun to get leaf temp, then adjust the offset variable in the meter setup EVERY time you want an accurate reading.
Those meters kill or greatly damage a lot of crops because of this. If your using one and your plants are constantly starving and crashing this is likely why.
If VPD gets too high you pull water thru the plant faster than nutes can enter with the water intake at the roots, and starvation/deficiencies are guaranteed.
If it goes in the other direction the plants will constantly look fat and too wet, and bugs are on their way.
I don't enter my tent without an IR thermometer in my hand.
Other than keeping temp offset updated, the time of day is the other really important thing to remember.
You can check accurate VPD any time of day you like (accurate=proper leaf temp offset) but only make adjustments based on the reading you take at 10 hours after lights on. If you make adjustments at earlier times then again, your plants will suffer.
VPD is also a very excellent way to dial your light in, far more accurate than a light meter, but thats a whole other rabbit hole.
There's simply no reason to take leaf temperature offset every time you want to take a reading. The offset very, very rarely changes and the only time it's not been -2° in three years of using VPD is that, for my last grow, I added fans to get to 2 meters/second of wind speed and that too my offset to -4.
The meter doesn't have anything to do with it. "Attack of the Killer Thermometer" — does that make any sense?
That's absolute bunk. VPD is nothing more than one number instead of two numbers. If a grower decides to change nutrient strength when VPD is very high, there's simply no reason to wait a magical number of hours "after the lights go on".
Again, no basis in reality.
And then there’s chocolate OG that makes me chilly and completely unable to speak coherently for at least an hour. Yes, I love it but only in a 4 times a year kind of love akin to makeup relations
lol I wasn't about to play unnice. I'm good. I didn't want you to give VPD a whirl without knowing the pitfalls is all, but your not using it so it's all good.
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You Are
I didn't want you to give VPD a whirl without knowing the pitfalls is all, but your not using it so it's all good.
Thank you !
