Vaper Pressure Deficit: VPD Chart

[ppm Charlie]

Here is what I do for VPD for the past 6 years.
First two weeks I am at 78-82⁰ and 75-80% humidity.
Weeks 3-8 I'm at 78-84⁰ and 65-70% humidity.
First week in flower I go to 77-80⁰ and 60-65% humidity.
Second week I go to 76-78⁰ and then each week until harvest I drop the humidity by 5% while keeping the temp between 75-77⁰ until harvest.

Last week or so I'm in the 30s for humidity.

I am working slowly to get absolute control my grow humidity and temp. It takes work and observations to get a system exactly right. Sounds like to got it solved.

 

[ppm Charlie]

A lot of LEDs have infrared diodes now. I don't have any leaf temp readings under them other than what the back of my hand says, but it definitely feels warmer than my older lights without IR diodes.

True.

 

[Nunyabiz]

I have also recently been heating my water to 74⁰ so it doesn't cool down the root zone.
The water coming from my hose through the filter is 46⁰ this time of year.
And I water every 24 hours so that cold of water that often would keep my root zone way to cold, probably be lucky to stay in mid 60s.
My root zone stays a pretty constant 69-73⁰ when watering daily with 74⁰ super oxygenated water.
I super oxygenate my water no matter what but it is very important when heating your water because oxygen levels go down as water warms.
Ideally I think its 73⁰ that you can go up to before it starts to affect nutrient absorption because of lower oxygen levels.
But I super oxygenate my water to as high as I can get it at 74⁰ so should be absorbing nutrients really well.

I think warm oxygenated water is good for soil life, microbes, worms, bugs etc and for the roots.

 

[ppm Charlie]

I have also recently been heating my water to 74⁰ so it doesn't cool down the root zone.
The water coming from my hose through the filter is 46⁰ this time of year.
And I water every 24 hours so that cold of water that often would keep my root zone way to cold, probably be lucky to stay in mid 60s.
My root zone stays a pretty constant 69-73⁰ when watering daily with 74⁰ super oxygenated water.
I super oxygenate my water no matter what but it is very important when heating your water because oxygen levels go down as water warms.
Ideally I think its 73⁰ that you can go up to before it starts to affect nutrient absorption because of lower oxygen levels.
But I super oxygenate my water to as high as I can get it at 74⁰ so should be absorbing nutrients really well.

I think warm oxygenated water is good for soil life, microbes, worms, bugs etc and for the roots.

...it's the details that matter most. 46 deg F water = springtime in Antarctica.

 

[OGeMann]

I have also recently been heating my water to 74⁰ so it doesn't cool down the root zone.
The water coming from my hose through the filter is 46⁰ this time of year.
And I water every 24 hours so that cold of water that often would keep my root zone way to cold, probably be lucky to stay in mid 60s.
My root zone stays a pretty constant 69-73⁰ when watering daily with 74⁰ super oxygenated water.
I super oxygenate my water no matter what but it is very important when heating your water because oxygen levels go down as water warms.
Ideally I think its 73⁰ that you can go up to before it starts to affect nutrient absorption because of lower oxygen levels.
But I super oxygenate my water to as high as I can get it at 74⁰ so should be absorbing nutrients really well.

I think warm oxygenated water is good for soil life, microbes, worms, bugs etc and for the roots.

2 yrs late on this subject matter, I heat my water to 72° and you say super oxygenated water, what do you mean by that??? are you preferring to peroxide H2o2

 

[OGeMann]

I what this thread to keep going, lots of good information on VPD, I am using LED its a 600 R-spec and been following and reading and lots of research on VPD. This time around I have been going by leaf temp and not air temps as i done previous grows. I am at 3 weeks with 2 Blue Dream-(photo) and i am following leaf temp at 77°-78° so that is about a -2° as measured by my IR gun. The RH is 60%-65% I have a Pulse One that gives me readings of temp, RH and VPD, I have Inkbird controllers that controls Temps and Humidity. 6"-8" fans for exhaust and Intake both are run and controlled by my Inkbird controllers.

Back too VPD: As stated above with leaf temps it seems like I have a better control to go by leaf temps. I have screen shots of the Pulse One, As you can tell its stays pretty stable as long as I dont open the tent to take a peek at them (yes guilty as ever) the green lines are of VPD readings (((the gap in VPD is me taken leaf temps)))...
The next one is AVG and VAR(variance). As I can keep the temp stable enough and RH, VPD will be stable as long as I dont disturb them like opening the tent to look at them even though I have a camera.

Here is my setup as of now, as they get bigger I will add a scrog net and the heater will be removed as the tent is in the basement. I am really impressed with those evaporative humidifier as it does not leave the white residue as the ultrasonic ones do, also the warm mist humidifier is doing good too, was a little worried about heat but its not to bad, they like it hot and muggy....

 

[Nunyabiz]

2 yrs late on this subject matter, I heat my water to 72° and you say super oxygenated water, what do you mean by that??? are you preferring to peroxide H2o2

No, I use o2 emitters.
My water looks like a fine beer, its full of micro-fine bubbles.