So I’ve seen a huge amount of people having issues with low temps/slowed growth under LED fixtures. The lack of radiant heat is most definitely the cause in many cases. Supplemental radiant heat can be used such as heat mats, added fluorescents or even a heat lamp. Especially in the seedling stage and early Veg stage cannabis is highly susceptible to big temp swings, and lack of radiant heat. I would appreciate anyone with more info , tips, tricks etc. any other cultivators have used to solve this problem. This was actually brought to my attention by @ifish and since addressing this issue my starts haven’t looked or been healthier since I switched to LED. I saw at least 4 threads this morning alone having this issue so I figured I would start a thread to bring this to more peoples attention and hopefully we can help some people avoid this situation altogether.
I just run my fan at a higher setpoint, the LEDs still give off heat. Somewhere between 81-84°F gives me a nice 75°F leaf surface temperature. Don’t forget about VPD as well. 
Almost Exactly where I keep mine actually 81-85 daytime temps leaves me around 75-78 leaf temp.
I know vpd is definitely different for led… I’m using led and still working on it plus correct nute ratios… plus cal mag and ro water issues. Getting aggravated to say the least lol
You are correct the fixture itself gives off heat but the beams do not without added IR
Was going to say 85 is supposed to be optimal via blackdog led…
I experience massive temperature swings because of leaky windows and full sun windows during the day.
Currently it’s overcast:
Yes it can be super frustrating. That’s why I think I needed to make this to avoid others the issues so many of us have battled and took forever to fix lol.
For sure!!! Props!!!
Wow, I feel you on that my old house had the leakiest windows and worst insulation ever. Constant issues, especially in the winter.
Yes, but the whole point is leaf surface temperatures are what count. With HID lighting, the IR heats up the leaf surface usually close to ambient air temps. With LED, there is less of that IR so leaf surface temperatures are usually 5-10°F lower than ambient air temps. This has been around since the old GrowMau5 COB videos.
This is a relatively new build 
I’m more of a range guy than an ideal guy and as long as things are reasonable I see no problems.
Man I need a temp gun. And now a new apogee meter as it appears I lost it during my move, or it was stolen but I don’t see how that’s possible. Grrrr. Been looking for 5 days, nowhere left to look unfortunately. Dammit 
right i mean a desert plant will be different than a colder climate plant as well ya know? while growing indoor…
Functional AND fun.
Yes but the 11000000 people who don’t know this and have been asking me about this constantly for months do not know this and definitely need to learn/be told. My new lights have IR so this is no longer needed in my case but for so so many it very much is
leaf surface temps are typically 3 degrees colder than the ambient air due to transpiration
I swear I’m adding a new gadget or two to the whiteboard daily lately. I gotta stop spending cash I don’t have 
lol
tell me about it…i just spent hundreds on a second tent and more lights a digital microscope… list goes on… i stop at nothing for my passions