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Interesting Info On Led Growing

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Interesting Info On Led Growing

Shawnery 52 Replies 33,313 Views
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Shawnery

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#1
I did some research yesterday and found info that suggests that led fixtures should be run about 10 degrees warmer than HPS or anything with IR wavelength.

The scientific reasoning behind this was that IR wavelengths add a good amount of heat within the actual leaf structure beyond that of temperature of the canopy space its self.

I'm going to try this out next time and see how it goes. This was information supplied by a respected led light company. I tried to find it again but I can't seem to find it. I'll keep looking since I know, without data it didn't happen.
 
#4
How do you run your fixture 10 degrees warmer? Or are you talking about the grow space that should be 10 degrees warmer? Just curious. Good info tho.
 
#5
Air temp can be higher in the room because the actual leaf temp is lower without the IR. So you can run the room hotter without shutting the plant down.

Something I had brought up in a few other threads but it is a hard concept for some and I had to think thru it as well when a master grower pointed it out to me.
 
#6
DGP said:
Air temp can be higher in the room because the actual leaf temp is lower without the IR. So you can run the room hotter without shutting the plant down.

Something I had brought up in a few other threads but it is a hard concept for some and I had to think thru it as well when a master grower pointed it out to me.
Click to expand...

Ok that's what I thought. Makes sense. Thanks for clarifying!

I'm not sure i'd raise the room/space temp on purpose unless you were at the bottom of the ideal temp range. But it is nice to know you can run hotter and not have any issues. That extra 10 degrees will help a lot of people as keeping temps down can be difficult in some areas without added cooling (and added expense).
 
#7
I use it to hit my ideal growth temp for a given strain and to cut cooling costs as much as I can. Small changes can make significant improvements in the growing environment.
 
#8
That's the point,

The ideal grow temp is arguably around 78 degrees but that's based on the effect of IR spectrum.

If you're running LEDs at 78 degrees they're not at the "ideal temperature" anymore since the leaf temp is lower from lack of IR.

So you would now need to run your room at a higher temp to gain the same benefits of running at 78 with other lighting.
 
#10
It's going to vary by setup bc no one keeps lights same distance same fans etc etc. I had the temp gun given to me so idk how much they are but it sure is handy just point and it tells ya lol !
 
#11
Infrared Radiation Creates Leaf Temperature Gradients Down the Canopy
HPS bulbs emit a large infrared peak between 800nm and 900nm. This infrared peak significantly increases leaf temperatures at the top of the canopy, where most of the infrared light is absorbed. When examining the differences between leaf temperatures of plants grown in the same room under either HPS or LED lights, we will see significant temperature differences that infrared light causes.

In one of our studies, cannabis consultant Dr. Matt Wheatley measured the photosynthetic activity and internal leaf temperature of leaves at different distances from the light source. The internal leaf temperature measurements were very clear. The leaves of plants under LEDs did not show an increase for internal leaf temperature significantly above the ambient room temp at any distance between 2’ and 4’ from the lamp. In contrast, the leaves of plants under the HPS lamps showed a wide range of internal temperatures; the highest temps were apparent at the top of the canopy and lowest internal leaf temperatures were at the bottom of the canopy. This partially explains why HPS lamps produce top-heavy crops while LED lighting creates a more uniform canopy.

Since the rate of carbon fixation by RuBisCO is affected by leaf temperature and CO2 concentration, increasing the ambient temperature in LED-lit rooms will increase the rate of photosynthesis and plant growth.

Raise the Temperature in a LED Room
Based on scientific study and experimentation, Cannabis Consultant Dr. Matt Wheatley has found that an increase in the ambient room temperature of 5-7°C in LED-lit rooms relative to temperatures in HPS grow rooms is necessary to achieve similar internal leaf temperatures and plant growth rates as those experienced by plants in HPS-lit rooms. Keep in mind that as the ambient room temperature increases, the relative humidity decreases, and proportionate adjustments should be made to the relative humidity to adjust your Vapor Pressure Deficits.



About LumiGrow, Inc.
 
#13
Ar.BsG said:
I run leds and have a infrared temp gun room temps 85 leaf temp 78.
Click to expand...

The cut and paste was in response to this statement. After reading this statement that would seem to be contradictory to the info I posted I did some more research. Glad I did because I wasn't quiet explaining it correctly.

As you can see from the article, the surface is not what actually heats up from the IR spectrum, it's actually the inner structure.

This could be one reason why people may not be getting the similar results to other light sources with led's. Ten degrees is a lot in terms of perfect growing environment for growing cannabis.

It would be interesting for someone to do a test with lighting and run one plant at the accepted 78 degrees under led and than another with the temp at 88. It's the only way to know for sure what the differences might be but the science seems straightforward.

To me this seems like a big deal???

P.s. I was thinking of putting it in the indoor section because it's not just about led's but about the temp needed to grow indoors with led's. Not to mention I was thinking not as many people read this section in comparison. I thought out of all the posts I've made this one actually may be of use to a number of people.
 
#15
I use cob leds and my max temp in the tent is 88F,plants grow,smell,produce same as they did when I ran cheap LEDs with IR diodes and hps,with that said I havent tried keeping the temps lower to see if that slows growth at all,but it sure doesn't seem to hurt anything and as mentioned before,saves a bit on cooling costs.
 
#16
74 degrees peak room temp under leds. Of course there are supplemental red, ir and uv diodes in the build.
DSCN0924
 
#17
The point wasn't what everyone runs or doesn't run but the scientific evidence to suggest that led temps should be about 10 degrees warmer.

If you're running LEDs with IR than 78 or so is perfect, according to studies. If you're just running LEDs than 88 should be around the sweet spot.

I wouldn't dare guess as to the validity of this study as I'm not a scientist or a botanist.
 
#18
88f is a bit high for led ime,but with co2 88 to 90plus would be fine.i run 4 or 5f higher under my setups and they seem to grow as they did under his minus the extra large I used to get under hid. Surface temps will effect inner leaf temps,that's just common sense.unless you had some crazy x-ray lights you can't really raise inner temps while keeping the surface cooler lol. So basically leaf temps are just leaf temps,and ir lighting will heat up most anything it hits including leaves,walls,floors,water tanks ect.hps=more heat LED=more gooder haha.
 
#20
Just did a side by with led right next to cmh bulbs in the same room and saw no less performance on the led side.the led side produced about 30 percent more bud than the cmh.
I run 82 veg,80 early flower,78 mid and 75 late than bring it down to 74 last week.
3 wall thermometers with a mini split and the room ambient temp is dead nuts where I set it.
I dont pay any attention to radiant heat.it has never made a difference in any of my situations.
Humidity and co2 levels are the big dogs in my grow rooms.plants can tolerate radiant heat but I never saw any growth spurts of over the other.
Humidity plays a bigger role in how a plant deals with any given temp.
 
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