Lighting Ideal range for leaf surface temp (LST)

[lunarman]

There was surprisingly little on a google search on this when you include the term 'ideal'. There is a ton of info where to put a temp probe in your garden or what factors change temperature or using IR to measure it. But little on what is the LST range we want for weed.

Love to know what is a good range for LST. And since this is a COB discussion board I'm not asking in the context of using autocob height over canopy to control LST, like one had to do back in the old HID lighting days. I'm asking more in the context of taking the ambient tent temp and speed controls on my inline exhaust and fresh air fans and the speed and position of the circulating fans.

I haven't checked LST in ages. Really since I got autocobs I didn't think about it. But now I do. Today my LST (using IR) was 64 degrees F with the current heater/fan setup.

 

[HemiSync]

There was surprisingly little on a google search on this when you include the term 'ideal'. There is a ton of info where to put a temp probe in your garden or what factors change temperature or using IR to measure it. But little on what is the LST range we want for weed.

Love to know what is a good range for LST. And since this is a COB discussion board I'm not asking in the context of using autocob height over canopy to control LST, like one had to do back in the old HID lighting days. I'm asking more in the context of taking the ambient tent temp and speed controls on my inline exhaust and fresh air fans and the speed and position of the circulating fans.

I haven't checked LST in ages. Really since I got autocobs I didn't think about it. But now I do. Today my LST (using IR) was 64 degrees F with the current heater/fan setup.

I’ve never even considered it before other than keeping the ambient temps between 68 and 82 degrees. I do control my fan setup with a thermostat at the back of the tent strapped to a pole just above the height of the canopy. You can see it in the pics of my grows. It turns the fans on at 80f degrees or could be reversed if using some kind of heating unit. I also have a wireless temp probe hanging in my tent, dead center, at canopy height. I can track my highs and lows. My current setup keeps the tent between 72-80f and the humidity is ranging between 30-70% with the highest humidity occurring during lights out. Lights go out, fan goes off, and girls start transpiring.

I know one of the members here use to control temp and humidity down to the degree or better. He had a self built environmental control unit. Let see if I can figure out who that is and get back to you.

 

[Heavily Medicated]

I use a laser temp gun and I try to keep my plant surface temperature between 70-80 F. In hot summer time, I've had plant surface temps up to 85 F with no noticeable problems. At around 85 F a plant starts to close stomates and transpiration drops slowing growth proportionately.

 

[thetreeman]

Id say around 80f is pretty close to ideal, with RH around 60% in veg and drop it down to 45-50 in flower.

 

[Muddy]

The conventional wisdom with HID was to have the temp at the canopy top between 78 - 80 degrees. With the cooler running LEDs the range goes up to 80 - 82, with 82 providing the best transpiration. During lights off the temp should drop about 10 degrees. If you're supplementing with CO2, temps should go a bit higher, in the 83 - 85 range. CO2 is better absorbed in that range. Once the plants are nearing the end of their life temps can be cut back to simulate the end of the growing season outdoors. Dropping it down to 70 lights on is best if you can manage it.

 

[HemiSync]

After my last mistake with VPD, I will be taking vapor pressure deficient into account on all my grows. I can almost always control my temps in my grow area but have major issues with humidity, usually just too low.

 

[Simplicio]

There was surprisingly little on a google search on this when you include the term 'ideal'. There is a ton of info where to put a temp probe in your garden or what factors change temperature or using IR to measure it. But little on what is the LST range we want for weed.

Love to know what is a good range for LST. And since this is a COB discussion board I'm not asking in the context of using autocob height over canopy to control LST, like one had to do back in the old HID lighting days. I'm asking more in the context of taking the ambient tent temp and speed controls on my inline exhaust and fresh air fans and the speed and position of the circulating fans.

I haven't checked LST in ages. Really since I got autocobs I didn't think about it. But now I do. Today my LST (using IR) was 64 degrees F with the current heater/fan setup.

According to an infrared thermometer, my leaf temps average about 7 degrees F lower than tent air temp.
The plant seems able to keep it somewhat constant, regardless of air temp.
Leaf temp is the best temp to use when paying attention to Vapor Pressure Deficit.