Leaf surface temp variables

Skylander · Sep 21, 2020

On my 5th cycle using no-till organic with Blumats. Sealed room with led lighting and supplemental CO2 at 1200 ppm (100 deadband). Everything is going great but I always look for ways to improve and squeeze that extra 5-15 percent. So from first hand observation temps 80-82f is my sweet spot for my preferred strain. However, I always see people on here recommend temps 84 to 86 degrees because of co2 use. Am I missing a variable or is this just another case of people repeating what they’ve heard vs what they’ve actually done?

Renfro · Sep 22, 2020

In my LED grow, albeit a small grow compared to my HID grow, I had my canopy at 82 - 84F and my plants were growing ok, I cranked it up to 86 - 88F, and the plants exploded. CO2 around 600 - 800, just bleeds over from my flowering rooms so it is what it is. Nugs extremely dense, denser than under my HPS not fluffy like hot flower.

I recently snagged an IR camera, I plan to use that on my next LED run to get a better picture of whats going on with the leaf surface temps.

JonCreighton · Sep 22, 2020

Renfro said:
In my LED grow, albeit a small grow compared to my HID grow, I had my canopy at 82 - 84F and my plants were growing ok, I cranked it up to 86 - 88F, and the plants exploded. CO2 around 600 - 800, just bleeds over from my flowering rooms so it is what it is. Nugs extremely dense, denser than under my HPS not fluffy like hot flower.

I recently snagged an IR camera, I plan to use that on my next LED run to get a better picture of whats going on with the leaf surface temps.

u keepin the room that high thru most of flower? the humidity high aswell?

im just curious cuz im pushing temps up to 85 for the first time.... going great... but think maybe wise to start moving temp and humidity down as flower progresses...?

when u changed the room and the plants exploded... do u mean u just changed the room temp conditions... or something w the lights?

Skylander · Sep 22, 2020

Renfro said:
In my LED grow, albeit a small grow compared to my HID grow, I had my canopy at 82 - 84F and my plants were growing ok, I cranked it up to 86 - 88F, and the plants exploded. CO2 around 600 - 800, just bleeds over from my flowering rooms so it is what it is. Nugs extremely dense, denser than under my HPS not fluffy like hot flower.

I recently snagged an IR camera, I plan to use that on my next LED run to get a better picture of whats going on with the leaf surface temps.

Are you increasing your light output to get to those temps? That might be my problem now that I think about it. I have to increase my light intensity to get above 82f. I think it might just be light stress instead of heat stress. I have a 2ton mini-split and even when I set my temp to 86 it still never gets above 82.7 exactly.

Renfro · Sep 22, 2020

Skylander said:
Are you increasing your light output to get to those temps? That might be my problem now that I think about it. I have to increase my light intensity to get above 82f. I think it might just be light stress instead of heat stress. I have a 2ton mini-split and even when I set my temp to 86 it still never gets above 82.7 exactly.

My LED tent is in a veg room that has lights in it. So the tent just draws air from and back to that room. It makes it a little warmer than my veg room.

JonCreighton · Sep 22, 2020

this graph would indicate in terms of photosynthesis you should be pushing the temp as high as safely possible... is what holds people back in veg disease?... im curious how hot people have pushed it in flower esp late flower... and im curious if you would try and get ur leaf temp as high as possible while keeping the room little more moderate.. or if it would be just keep the room that high....

Renfro · Sep 22, 2020

JonCreighton said:
do u mean u just changed the room temp conditions... or something w the lights?

I just turned up the temp on the AC in that veg room, the room that flowering tent gets it's air from. I wanted to get a warmer canopy temperature in the veg room and knew the tent would be riding a little higher. Figured I would let it ride, I did speed up that tent blower a little but the tent is already trying to implode with two high CFM kits. So the tent is always a degree or two warmer than the veg room.

JonCreighton said:
this graph would indicate in terms of photosynthesis you should be pushing the temp as high as safely possible... is what holds people back in veg disease?... im curious how hot people have pushed it in flower esp late flower... and im curious if you would try and get ur leaf temp as high as possible while keeping the room little more moderate.. or if it would be just keep the room that high....

I suppose that largely depends on the light source. With LED lacking all the IR that HPS pumps out you have to warm the air to get leaf surface temps up. With HPS the IR warms the leaf surfaces a lot and you have to keep the air cooler. As to hot hot I have ever pushed things and had good results was under HPS with temps up around 88 - 89F and CO2 at 1500 PPM with RH% up around 70%. The only way I was able to make that work for me was the strain I grew was impervious to mold / bud rot and I didn't have big night temp drops. Flood and drain hydro. Yields were extreme and growth rates were crazy. That was many years ago and a sealed room was a must for stealth. A big factor is the effects of RH% on VPD and the effects of temperature on RH% (room cooling causing RH% to spike). Strain is also a big factor, some strains like it hot and some don't. Generally sativa dominant varieties are the ones that will take the heat and indica dominant ones like it a bit on the cooler side. Strains with darker leaves (usually indica dominant) also seem to like it cooler, maybe because of the IR??? Fine tuning a room beyond a certain point is useless unless you are mono cropping. You can however put "cooler" strains under less direct lighting, this works best with HID due to the IR.

To tune your environment for the best results will require precise control on RH% as well as temperature. This can often include raising the RH%. Until my plants hit a certain level of biomass / cuft ratio I have to run swamp coolers in my rooms to raise the RH%. Once the plants are transpiring enough water to keep the RH% up I don't need the swamp coolers and when the plants are really big in late flower I am running dehumidifiers during the dark period as the AC pulls enough when my lights are on.

I probably didn't answer any of your questions, lol I am pretty stoned right now. Hopefully you find something useful in there.

JonCreighton · Sep 25, 2020

Renfro said:
I just turned up the temp on the AC in that veg room, the room that flowering tent gets it's air from. I wanted to get a warmer canopy temperature in the veg room and knew the tent would be riding a little higher. Figured I would let it ride, I did speed up that tent blower a little but the tent is already trying to implode with two high CFM kits. So the tent is always a degree or two warmer than the veg room.

I suppose that largely depends on the light source. With LED lacking all the IR that HPS pumps out you have to warm the air to get leaf surface temps up. With HPS the IR warms the leaf surfaces a lot and you have to keep the air cooler. As to hot hot I have ever pushed things and had good results was under HPS with temps up around 88 - 89F and CO2 at 1500 PPM with RH% up around 70%. The only way I was able to make that work for me was the strain I grew was impervious to mold / bud rot and I didn't have big night temp drops. Flood and drain hydro. Yields were extreme and growth rates were crazy. That was many years ago and a sealed room was a must for stealth. A big factor is the effects of RH% on VPD and the effects of temperature on RH% (room cooling causing RH% to spike). Strain is also a big factor, some strains like it hot and some don't. Generally sativa dominant varieties are the ones that will take the heat and indica dominant ones like it a bit on the cooler side. Strains with darker leaves (usually indica dominant) also seem to like it cooler, maybe because of the IR??? Fine tuning a room beyond a certain point is useless unless you are mono cropping. You can however put "cooler" strains under less direct lighting, this works best with HID due to the IR.

To tune your environment for the best results will require precise control on RH% as well as temperature. This can often include raising the RH%. Until my plants hit a certain level of biomass / cuft ratio I have to run swamp coolers in my rooms to raise the RH%. Once the plants are transpiring enough water to keep the RH% up I don't need the swamp coolers and when the plants are really big in late flower I am running dehumidifiers during the dark period as the AC pulls enough when my lights are on.

I probably didn't answer any of your questions, lol I am pretty stoned right now. Hopefully you find something useful in there.

no no.. great answer i got it all... i will check into the ir stuff when i get some time..

why lower the humidity during late flower... like whats driving that... should i be looking fora different vpd mid to late flower... or is it the relative hunmidity driving it here? i guess what im asking kinda is... are u changin ur temp w the humidty and trying to maintain a "baseline" vpd or is it a RH and VPD change as u go in flower...

Leaf surface temp variables

Skylander

Well-Known Member

Renfro

Well-Known Member

JonCreighton

Well-Known Member

Skylander

Well-Known Member

Renfro

Well-Known Member

JonCreighton

Well-Known Member

Attachments

Renfro

Well-Known Member

JonCreighton

Well-Known Member

Similar threads