Leaf temp, ambient temp and VPD
Posted: Sat Feb 09, 2019 8:28 pm
High all,
I am new to growing in a tent, and like many, I'm trying to optimize my environmentals.
There is a lot of conflicting information out there about VPD and the Boogeyman (powdery mildew, or PM) and I'm looking for some help to make sense of it all.
Here the chart I started working from, published by Fluence;
https://www.kisorganics.com/pages/canna ... episode-10
The values are very percise, but I found it cumbersome to work with.
Here is my interpretation,
I've been trying to maintain a 1.5kPa deficit, and have noticed seedlings at 28°C / 65%RH are growing much more vigorously than those at 25°C / 55%RH.
Those are atmospheric temps. Leaf temps are ~27°C and ~23°C respectively.
Looking forward, I plan to push humidity and temperature in veg. Aim for 28°C on the leaf, and then add humidity until I get a 1.0kPa deficit. Is this relative to ambient air temp? Or leaf temp? Any wisdom in splitting the difference, or 'averaging' as a scientist would say?
I've had a couple of times where the tent hit the dew point at lights out. WOW, there's a lot of water in that hot humid air. Getting a few good airchanges in right at lights out is critical to keeping the dew point low and the humidity stable as the temp drops ~5°C
My real question is; what is the best way to dial a flowering tent in? I'm planning to start out with the 'status quo' 25°C / 55% RH, but that will mean bringing the lights VERY close to get 28°C leaf temp. Is this all there is to it?
Outdoor plants hit the dew point consistently. Air circulation is key. I imagine altitude plays a part here as well, i.e. someone growing at sea level will not have the same results as someone growing at 2500m, so please include your altitude as well. I would love some technical input on how to give my ladies the best environment possible. For reference I am at about 700m / 2300ft,
Thanks, and forgive me if this has been covered elsewhere. I did a search, and if I missed it please point me there!
Any reference material, and links are welcome. Thanks!
I am new to growing in a tent, and like many, I'm trying to optimize my environmentals.
There is a lot of conflicting information out there about VPD and the Boogeyman (powdery mildew, or PM) and I'm looking for some help to make sense of it all.
Here the chart I started working from, published by Fluence;
https://www.kisorganics.com/pages/canna ... episode-10
The values are very percise, but I found it cumbersome to work with.
Here is my interpretation,
I've been trying to maintain a 1.5kPa deficit, and have noticed seedlings at 28°C / 65%RH are growing much more vigorously than those at 25°C / 55%RH.
Those are atmospheric temps. Leaf temps are ~27°C and ~23°C respectively.
Looking forward, I plan to push humidity and temperature in veg. Aim for 28°C on the leaf, and then add humidity until I get a 1.0kPa deficit. Is this relative to ambient air temp? Or leaf temp? Any wisdom in splitting the difference, or 'averaging' as a scientist would say?
I've had a couple of times where the tent hit the dew point at lights out. WOW, there's a lot of water in that hot humid air. Getting a few good airchanges in right at lights out is critical to keeping the dew point low and the humidity stable as the temp drops ~5°C
My real question is; what is the best way to dial a flowering tent in? I'm planning to start out with the 'status quo' 25°C / 55% RH, but that will mean bringing the lights VERY close to get 28°C leaf temp. Is this all there is to it?
Outdoor plants hit the dew point consistently. Air circulation is key. I imagine altitude plays a part here as well, i.e. someone growing at sea level will not have the same results as someone growing at 2500m, so please include your altitude as well. I would love some technical input on how to give my ladies the best environment possible. For reference I am at about 700m / 2300ft,
Thanks, and forgive me if this has been covered elsewhere. I did a search, and if I missed it please point me there!
Any reference material, and links are welcome. Thanks!