jack06041989
Active Member
So when trying to find out your VPD, how does it work? do you take the leaf temp with lights on or off? Do you use the room temperature with lights on or off? Is there like a typical/average VPD that’s best to work to?
VPD..
- Thread starter jack06041989
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jondamon
Well-Known Member
Like you I tend to keep my RH +50% for veg and -50% for flower.
if you get hung up in all the VPD charts you end up
Chasing your tail and for most personal grows it’s just not viable to chase it all the time.
if you’re a commercial grower then VPD can play a vital role with your full environmental controllers.
start by dialing in your room environment as best you can and maximise its efficiency without getting bogged down with Vapour Pressure Deficits.
You need to have the right chart to take the right measurements.
here is a link to charts that you can set depending on your leaf temp( which is what really matters).
www.dimluxlighting.com
I personally use the chart for zero difference between room temp and leaf temp. Then I mesure leave temp with a cheep infrared temp gun. Then use the chart by your leaf temp number.
I take the temperature of the leaf when the room is at your set temperature.
here is a link to charts that you can set depending on your leaf temp( which is what really matters).
Vapor Pressure Deficit - The Ultimate Guide - Dimlux Lighting - The Best Grow Lights
Simply put, Vapor Pressure Deficit measures the difference between the amount of drying power the atmosphere is exerting upon your plants. VPD is the key...
www.dimluxlighting.com
I personally use the chart for zero difference between room temp and leaf temp. Then I mesure leave temp with a cheep infrared temp gun. Then use the chart by your leaf temp number.
I take the temperature of the leaf when the room is at your set temperature.
jack06041989
Active Member
Is there quite a difference between leaf temp then ? My room is at 28 degrees is there like a normal leaf temp for that temperature? Or is it strain dependent ?You need to have the right chart to take the right measurements.
here is a link to charts that you can set depending on your leaf temp( which is what really matters).
Vapor Pressure Deficit - The Ultimate Guide - Dimlux Lighting - The Best Grow Lights
Simply put, Vapor Pressure Deficit measures the difference between the amount of drying power the atmosphere is exerting upon your plants. VPD is the key...
I personally use the chart for zero difference between room temp and leaf temp. Then I mesure leave temp with a cheep infrared temp gun. Then use the chart by your leaf temp number.
I take the temperature of the leaf when the room is at your set temperature.
Depending on the lights you are using.
I grow with Cob leds. I am finding at 80F room temp. My leaf temp is 76-77F.
With HPS lights you will see leaf temps higher then your room temp.
as far as I have seen it’s not strain depending
BBQtoast
Well-Known Member
You measure the leaf boundary layer, temps of everything, water potential of leaf, air humidity and then plug it into a computer program capable of doing all the calculations.
If you just plot temperature and humidity you get a chart that doesn't help you grow, it's a complex idea we can avoid by measuring other things like plant water use or transpiration and humidity doesn't change much compared to all the other inputs and outputs used to come to a healthy plant growth environment.
If you just plot temperature and humidity you get a chart that doesn't help you grow, it's a complex idea we can avoid by measuring other things like plant water use or transpiration and humidity doesn't change much compared to all the other inputs and outputs used to come to a healthy plant growth environment.