What is the importance of far red light?

Advanced Techniques
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Here’s a video you may like, this is sound info.
This should give you a good base of understanding of Far red light.

How Does Red And Far-Red Light Impact Crops?
I would like you to meet my main man Bruce!

There are other uses for red and far-red light in terms of photoperiodism and flowering response.
Research “night break” and “end-of-day” far-red light treatments, as well as the other topics.

Cannabis flowers due to changes in the night length (mainly), it senses the changing dark hours per day (diurnal period) using far-red light and red light. As well as Cannabis can flower due to age for some genotypes in unfavorable lighting conditions (like if the night isn’t long enough).

Far-red light is used for these things by growing plants, including Cannabis:
photosynthesis
photoperiodism
flowering induction (for some species, such as Cannabis sativa L.)
photomorphgensis
phototropism

Far-red isn’t something you would want to add to your spectrum normally, unless for very special use-cases (not photosynthesis)."

"FAR-RED:

In terms of not adding extra far-red I was referring to white light. If you have a LED array, you need to add far-red if it’s not already provided by the LEDs.

Read up on “phytochrome photoequilibrium,” “phytochrome,” “photoperiodism,” “red far-red ratio,” “shade avoidance reaction,” and “Emerson effect” to get a better understanding about use of far-red light by plants.

We want a red:far-red ratio of around 1 to less than 4 for indoor lighting. Sunlight is 1.05 to about 1.2 in the day, and about 0.6 to 0.8 at sunrise and sunset.

For PPE (aka PPS, “phytochrome photoequilibrium”) we want about 0.8 to 0.9, sunlight is about 0.5 to 0.72, except at sunrise and sunset when it’s much lower."

For more info on this topic, Google around for knna’s past writings on this topic of using far-red and red light to affect plant photoperiodism (for example, shorter nights to flower) and photomorphgensis; he has the best writing on this for Cannabis.

What I am referring to termed “shade avoidance reaction.”
It just means when there’s too much far-red light (725 to 735 nm; peak is 730 nm) relative to red light (655 to 665 nm; peak is 660 nm) the plant thinks it’s shaded, so it grows more (stretches) to try to get above the shade.

There are few research papers and studies you may want to review if you want more info about these topics. “End-of-day treatment” is also a common use for far-red LEDs:

Phytochrome allows plants to sense the color of light.

A higher proportion of FR light allows plants to detect when they are shaded.
Plants adapted for growth in full sun will display greater stem elongation when they are transferred to shade. They also develop smaller leaves and less branching. This change is due to greater proportion of Pr to Pfr.

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Bruce, there it is!

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Dr.Bruce is a damn wealth of knowledge! Can’t even count how many of his videos I’ve watched .

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I love Bruce! This video made me pull the tigger on a GLS G300 for that far red action!

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As do I! :heartbeat:
He is my go to when I have questions about light.

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Honestly for a wealth of knowledge all the way around. I really enjoyed the conversation he had with Mr. Grow it. Lots of good information that sifts through all the BS (bro science) haha

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I have not seen that one thanks, I will check it out when I have a moment. :sunglasses:

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Several years back I bought from Rapid Led a kit they had with 6 small 730 nm leds and a small meanwell driver and another same type led kit and 12 660 nm leds and another separate driver. I plug in the 660’s on same timer as main light when I flip and use the 730’s on a separate timer 10 minutes before lights out and until 10 minutes after lights out. I can’t swear any improvement but I’m pretty sure it’s still a benefit.

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I have a couple of the 4led 660 pucks in a 1m² tent. I have a vertical 4K CMH as the main power source. I’ve run this set-up a couple of times and I like the addition of the pucks. Hard to tell what is different, but something is improved.

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This is a neat trick!
This trick will allow you to increase your hours of light in flower beyond 12 hours as I mentioned in a previous post.
Sounds crazy right, if done right it will not even cause intersex issues in plants that are prone to it.
No guarantees with that though…LOL
There is a little info in the first post, but that warrants further discussion.

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Bruce’s channel is awesome! Lots of good info

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something similar here. 2x 24w panels with a 50/50 mix 660nm and 730nm. they turn on 15min before lights on and off 15min after.

plants seem to like it.

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I have 2x rapidled 730nm pucks that go into my flowering tents set for 15min right at lights off.

One I ran 3 tents in flower and was scratching my head why 1 set of plants wasn’t jumping into flower. Then i remembered this was the only tent without a puck. :rofl:

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But does anyone use the blue part of the spectrum to counteract the stretching far red tends induce?!?!

I love talking and learning about lighting :grin:

Did you guys know America’s top soil (it’s world wide but just as an example) is depleted something like 60% from just as many years ago? Cause we keep tilling and releasing cO2 and throwing chemical fertilizer on all the farm fields with virtually no organic matter and a bunch of other bad practices? I think indoor farming (outside of weed but definitely weed included) is gonna be a big industry for humanity one day cause we fucked the outdoors up cause of money.

Sorry for getting side tracked I’ve been drinking a little

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I have been told you can extend the flowering time beyond 12 hours with these methods.
I have also been told, 14 hours will work with most strains/cultivar with no ill effects unless you call increased yield an ill effect. :thinking:

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would you mind explaining that like I was a complete noob? how would they go by it?

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This is interesting stuff. When I first moved here about 6 years ago, I had read a little about red/far red light. I had always wondered if the HPS coming on/going off all at once was stressful to the plants.

I was at an industry fair at the local Grow store and I was talking to one of the light companies’ reps about it. They told me then that they were working on a system to mimic real life end of day, start of day, but I don’t remember hearing anything since.

I’ll go listen to the video. It’s been a while since I visited this info. I think it’s really cool that a few of you are doing it on your own.

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May I suggest as much research as you can stomach to go along with this…
You will do better with a complete understanding of what exactly it is you are doing, what your end goal is, and what results to expect in the end.

But super simply…
You simply add the appropriate red light to the end of your light cycle to allow the plants to fall asleep quicker, therefore a shorter dark period is needed to flower.
You are tricking the plant in a manner of speaking.

You can then set your timer for 14 hours on and 10 hours off.
Just make sure you use the red light at the end of the light cycle.
AKA, When the light shuts off.
At the start of the light cycle aka light turns on, is not really needed as far as my research shows.

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Blue, meaning lack of red/far red light reduces stretch mainly by not having the red involved.
It is really more about the ratio of red to far red that matters most.
All blue light is a ratio of 0-red to 0-far red, the ratio is even at “0” therefore you have stretch reduction.
I hope that helps…

Oh and the thing about the soil…Holy shit that is fucked up for sure.
Folks don’t realize how bad that shit really is.
Folks have been killin’ themselves for ruining their family heirloom land with chemicals.
We should start a whole thread on this topic, I could talk/rant for days so watch out…LOL

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I believe permaculture practices are slowly being adopted by a small percentage of the Ag community. It’s a start. After all, the prices of fertilizer continue to climb, and farmers could use a break on the money outlay. I believe farmers are (maybe not corporate) finally looking for a better way. Once they make the transition to microbes and natural nutrients, I think they would embrace it and work to get others to change the way they farm. I sure hope so, because the runoff from farms will continue to deteriorate the land, and the rivers, and the rivers pollute the ocean. Look at south Florida’s red tide bloom in the gulf. It’s caused by the runoff from the sugar plantations and refining facilities. The chemicals have finally begun to reach the gulf in larger amounts and the high nitrates are creating the dangerous algae blooms.

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