Under canopy LED’s
- Thread starter BH
- Start date
BH
Tha Dank Hoarder
FAVEN answered back ur questions and info via email . Hope this helps?
“
Far red can increase stretching. We suggest using far red for 5 mins after the lights shut off.
We suggest starting far-red sometime between weeks 1 and 2 of flower. Although that is with our lights. I have no idea what the quality or strength of the pucks you are currently using are. It's hard to give advice on other companies' equipment. If you are interested in Favens, I would be happy to work you up a quote.
I hope you have a great day! Talk with you soon. “
Castle Green Skull Labs
In Bloom
Not sure what you are running for lights, 15 mins before and after is better than 10-5. With 10-5 you are not getting full benefits and your giving more of hint that day/night is coming.
Far-red light (around 730 nm) rapidly shifts the plant’s phytochrome system from the active form (Pfr) to the inactive form (Pr) etc
With 15 mins you’re getting much more complete phytochrome pool, stronger more consistent end/start of day signaling, it can enhance faster stomatal opening/closing timed earlier metabolic shift into day/night respiration phase and most of all more photoperiod perception which is important in short day plants like cannabis.
Phytochrome conversion isn’t instantaneous across all tissues. Leaves at different angles and canopy depths receive different photon flux. Longer exposure increases the total
Conversion ration.
So 15 minutes tends to produce a more uniform whole-plant response.
Past a certain point, you hit diminishing returns, once phytochrome is mostly converted, more far-red doesn’t keep adding benefit.
I don’t run my far red during lights on till around week 3-4 of flower as I find the signaling to shade leaves tend to be a bit much. Node spacing will be further apart etc, I run mine around what would be mid day upper and lower far red with upper uv far red for 2-3 hours and uv 1-2 in between the far red period and I slowing bring that time down week by week till until end of flower.
Caddis
Zinger
I was running that timing, but I’m testing the cycle Faven is running. I have no idea what’s what?
I’ve had these pucks for years and there are still questions regarding their usage.
Are you basing your timing on experience or a study you read?
I made the mistake once getting in a hurry to run FR, made a stretchy mess.
Castle Green Skull Labs
In Bloom
Both, my experience and the science backs it up. I’m only running 45 watts total. 15 above canopy and 30 under canopy far red. Again anything over 15 mins is not really worth the gains and under 15 mins is again more of a “hint” not full on conversion of phytochrome. You’re still getting benefits, but not as much as you could be. You can skip running the extra far red during lights on and skip the Emerson effect and just using it for day/night signaling if you are getting to much stretch. Can I ask what your full lighting set up is?
Castle Green Skull Labs
In Bloom
One thing I will guarantee you, I will never push bro science. If it can’t be backed up by peer reviewed studies and data. Then you won’t hear it from me. I’m all about the science man!
Caddis
Zinger
I’m not going to dispute your findings, because I don’t know. However I have to believe Faven is working this based on science?
According to Dr Bugbee, we are just scratching the surface, so I’m not sure anyone has figured it out?
Lights I’m running:
(4) HLG Diablos
(16) Cree CX3590 80 3500K
(5) Atrium 50w strips 3600K (under canopy)
(2) Rapid LED Far Red
BH
Tha Dank Hoarder
castle, I agree with some of what you’re saying on phytochrome signaling and shade response, but I think a few parts are getting overstated a bit scientifically.
Far-red absolutely converts phytochrome from Pfr → Pr and EOD FR definitely works in cannabis. I also agree that excessive daytime FR can increase shade avoidance/stretch and wider node spacing.
Where I disagree is mainly the idea that 5–10 min is only giving the plant a “hint” that night is coming. Phytochrome conversion itself is actually very fast once enough 730nm photons hit the tissue. The bigger variable is usually photon dose and canopy penetration, not the plant slowly realizing night is happening.
A strong FR fixture for 5–10 minutes can often produce similar signaling to a weaker fixture run for 15+ minutes. That’s why commercial facilities don’t universally agree that 15 minutes is dramatically superior. If the response difference was huge, we’d see a much more standardized industry approach.
I also think the “stronger metabolic shift into respiration phase” and stomatal timing claims are a little more theoretical than proven in cannabis production specifically. There’s plant physiology behind it, but I haven’t really seen strong cannabis data showing major gains from 15 vs 5–10 min FR pulses alone. If u got a source of ur findings present it? I’m sure we all wanna see it and learn more.
You’re definitely right though that longer exposure can help canopy uniformity in dense rooms because lower leaves and angled leaves may receive less FR intensity. But that’s more of a canopy penetration/photon distribution issue than phytochrome conversion itself being slow biologically.
To me it’s more:
I think a lot of growers now overcomplicate FR and UV timing when overall PPFD, DLI, canopy management, VPD, and cultivar response usually move the needle more.
This isn’t a far red or Emerson effect thread so please keep thread focused on under canopy.
Far-red absolutely converts phytochrome from Pfr → Pr and EOD FR definitely works in cannabis. I also agree that excessive daytime FR can increase shade avoidance/stretch and wider node spacing.
Where I disagree is mainly the idea that 5–10 min is only giving the plant a “hint” that night is coming. Phytochrome conversion itself is actually very fast once enough 730nm photons hit the tissue. The bigger variable is usually photon dose and canopy penetration, not the plant slowly realizing night is happening.
A strong FR fixture for 5–10 minutes can often produce similar signaling to a weaker fixture run for 15+ minutes. That’s why commercial facilities don’t universally agree that 15 minutes is dramatically superior. If the response difference was huge, we’d see a much more standardized industry approach.
I also think the “stronger metabolic shift into respiration phase” and stomatal timing claims are a little more theoretical than proven in cannabis production specifically. There’s plant physiology behind it, but I haven’t really seen strong cannabis data showing major gains from 15 vs 5–10 min FR pulses alone. If u got a source of ur findings present it? I’m sure we all wanna see it and learn more.
You’re definitely right though that longer exposure can help canopy uniformity in dense rooms because lower leaves and angled leaves may receive less FR intensity. But that’s more of a canopy penetration/photon distribution issue than phytochrome conversion itself being slow biologically.
To me it’s more:
- first few minutes = most of the effect
- 5–10 min = usually sufficient if intensity is adequate
- 15 min = slightly more complete/uniform
- beyond that = diminishing returns fast
I think a lot of growers now overcomplicate FR and UV timing when overall PPFD, DLI, canopy management, VPD, and cultivar response usually move the needle more.
This isn’t a far red or Emerson effect thread so please keep thread focused on under canopy.
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Castle Green Skull Labs
In Bloom
Let me see if I can find the studies again, I agree with you that a lot of growers over complicate things when it comes to lighting and there is a lot of bro science and what not. Most of the studies data that I’ve come across are from based 5-30 Again there are so many variables from lighting fixtures, grow space etc. here is a basic link and there are links in it to a few studies.
The general consensus is 15 mins is roughly the sweet spot, less then will be incomplete conversion and over 15 returns diminish significantly. But again there are many many variables and people tend to over complicate things as you said before. I’m not saying that 15 mins is going to be perfect for everybody’s set up. But, generally 15 mins is more than sufficient vs 5-10. Running 15 mins, will generally let you run a 13/11 flowering schedule and potentially cut a week or two off flowering time. Now I’m not saying this is exact, you are right this is still being studied and new data is coming out all the time. Even studies on how green light can be helpful. Which people thought was safe and plants didn’t use green light etc.
Complete Lighting Science Guide | Far-Red EOD, PPFD, DLI & Advanced Techniques | Toledo Indoor Garden
Master grow light science: End-of-Day Far-Red (EOD-FR), phytochrome system, PPFD/DLI optimization, spectrum design, LED vs HPS comparison. Professional lighting techniques for maximum yield.
Chefdave
Tree of Life Genetics
I luv how all these light manufacturers say 25 to 30 percent increase in yield, are they including the extra 600 to 680 watts needed for every 32 to 36 sq. Of canopy space of under canopy lighting to be effective. Its a marketing gimmick, not the lighting but the absurd claim of 25 to 30 percent increase. Yield increases have to be measured by grams per watt period, why don't they show this, because they want to sell lights. I use undercanopy lighting, it works for increased lower canopy bud quality, including and most importantly a more consistent color top to bottom and density of flower, but no way in hell are you going to get the same yield as if you put those 600 to 680 watts used for undercanopy in another top lighted tent or room without undercanopy. I can get 2.2 to 2.3 lbs with 600 watts of top lighting. No way I'm getting that or anyone else adding 600 watts of undercanopy extra yield. I lost almost a half g a watt using uc, but color and quality it provides, demands a better price, so it all works out for me
