NEED HELP WITH VPD!! MY LEAFE TEMPS ARE BASSACKWARDS!!

[MIMedGrower]

Side question @Aqua Man

Do you know of a test that shows improvement using vpd parameters rather than just keeping temp and humidity in a hospitable range. Like 77 farenheight and 50% rh at the canopy?

I dont have the old links but many tests say marijuana is not effected by humidity much. Just temp.

No quality or yield increase or decrease with varying grow humidities.


I think maybe the popularity of vpd. Which was developed for greenhouse use to compensate for high temps. Is because of early led lamps with no ir.

But the solution was the manufacturers added ir not change grow parameters.

 

[Oa.ahhu]

Tell ya what... Grab a leaf and do top and bottom. Post the difference. But I can tell you that thermometer is nowhere near sensitive enough to

Without CO2 I would say 77f is a good target for leaf temps.

Will do next time im home, I'd bet it depends on a lot of things

 

[Aqua Man]

Side question @Aqua Man

Do you know of a test that shows improvement using vpd parameters rather than just keeping temp and humidity in a hospitable range. Like 77 farenheight and 50% rh at the canopy?

I dont have the old links but many tests say marijuana is not effected by humidity much. Just temp.

No quality or yield increase or decrease with varying grow humidities.


I think maybe the popularity of vpd. Which was developed for greenhouse use to compensate for high temps. Is because of early led lamps with no ir.

But the solution was the manufacturers added ir not change grow parameters.

I would have to dig through but I think I do... The key really being the leaf temps your absolutely right to my knowledge temperature is the bigger factor of the 2. The humidity is more about reducing the stress on a plant and regulating good transpiratation rates to supply adequate/ideal water and nutrients while aiding in regulating leaf temps.

 

[MIMedGrower]

I would have to dig through but I think I do... The key really being the leaf temps your absolutely right to my knowledge temperature is the bigger factor of the 2. The humidity is more about reducing the stress on a plant and regulating good transpiratation rates to supply adequate/ideal water and nutrients while aiding in regulating leaf temps.

Sorry for the homework bud. Obviously no rush. :-)

 

[Aqua Man]

Sorry for the homework bud. Obviously no rush. :-)

Hey no problem bro... Will get to it tonight for ya.

 

[MIMedGrower]

Hey no problem bro... Will get to it tonight for ya.

Thanks. I can always count on Superheroes. Even the goofy sea-farin’ one riding the pink seahorse. ;-)

 

[Aqua Man]

Thanks. I can always count on Superheroes. Even the goofy sea-farin’ one riding the pink seahorse. ;-)

Oh man I need to change this name lol. I hate superheroes. I wish I knew Aquaman was a superhero before.

Now where did that pink horse go lmao

 

[Aqua Man]

@MIMedGrower here is one study. I realize this is not cannabis but I'm sure you will agree that it is in fact very relevant. Picking through in between work stuff if you want a few more just let me know. I would also state that IMO as plant growth is increased VPD plays a larger role. The more light, media providing faster growth (ie aeroponics etc.) co2. The more impact can been seen from VPD. This is first hand observations on my part. I haven't found or looked for any studies to back that up but I feel very strongly about it.

Vapour pressure deficit control in relation to water transport and water productivity in greenhouse tomato production during summer

Although atmospheric vapour pressure deficit (VPD) has been widely recognized as the evaporative driving force for water transport, the potential to reduce plant water consumption and improve water productivity by regulating VPD is highly uncertain. To ...

www.ncbi.nlm.nih.gov

 

[Rickypohiogrower32]

I would have to dig through but I think I do... The key really being the leaf temps your absolutely right to my knowledge temperature is the bigger factor of the 2. The humidity is more about reducing the stress on a plant and regulating good transpiratation rates to supply adequate/ideal water and nutrients while aiding in regulating leaf temps.

I'm trying to use the information to make sure my light isn't to close!!! Like I said it's literally 10-12 inches from the conopy...

 

[Rickypohiogrower32]

Also to keep an ongoing note of things in case white powder I see moisture under a bunch of overlapping leaves so I defoliate but I can't keep up and eventually I'm supposed to stop lol

 

[Rickypohiogrower32]

Also to keep an ongoing note of things in case white powder I see moisture under a bunch of overlapping leaves so I defoliate but I can't keep up and eventually I'm supposed to stop lol

This 2x2x4 is very crowded lol

 

[Aqua Man]

Also to keep an ongoing note of things in case white powder I see moisture under a bunch of overlapping leaves so I defoliate but I can't keep up and eventually I'm supposed to stop lol

Eventually you will remove enough that they won't stack up

 

[MIMedGrower]

I'm trying to use the information to make sure my light isn't to close!!! Like I said it's literally 10-12 inches from the conopy...

Plant looks very healthy but the upper leaves are stressing a bit. I would back the light off a few inches and see how the leaves react. I like to see them flat and happy and relaxed looking if that makes sense.

 

[Rickypohiogrower32]

The under parts of leaves are giving me much higher reading between 80-84. And 76 on top is this normal?

 

[Rickypohiogrower32]

The under parts of leaves are giving me much higher reading between 80-84. And 76 on top is this normal?

And would you guys defoiate I'm in about week 2 or 3 of flowering

 

[Aqua Man]

The under parts of leaves are giving me much higher reading between 80-84. And 76 on top is this normal?

Just gonna say that's impossible.

 

[Rickypohiogrower32]

And would you guys defoiate I'm in about week 2 or 3 of flowering

And this is a sitiva dominant by the leaves and what I've researched bad azz Og cheese. Looking like it's gonna take forever...

 

[Rickypohiogrower32]

Just gonna say that's impossible.

Your right I was getting wall reading trying to take pictures and good Lazer spot lol

 

[Rickypohiogrower32]

Your right I was getting wall reading trying to take pictures and good Lazer spot lol

Temperature is the same basically top and bottom...

 

[Aqua Man]

Temperature is the same basically top and bottom...

Yeah I figured you were somehow missing the leaf. When taking leaf temps what I Donis take multiple readings and average them. Also look for any abnormally high ones so you can adjust that plant.