Has anyone heard of this photo flowering technique or is using this?

I just read this in an online article:

Most modern cultivars will happily flower under 13.5 hours of light. An effective lighting strategy to achieve this goal is to shift the photoperiod to a 12/12 IP for six to eight days to ensure a fulsome flowering response. The photoperiod can then be adjusted to a 13.5/10.5 IP for four or five weeks, and then back to a 12/12 IP for the final ripening stage.

Is anyone here using this or has heard of this? It’s new to me.


I’ve never seen anything so specific, but it is known that cannabis is capable of flowering with < 14 hours of light per day. Most growers select 12/12 and stay with it because it guarantees flowering for perhaps a stubborn plant and minimizes the risk of reveg. The DLI difference between 14 and 12 isn’t all that significant so you don’t lose much with 12/12.


Sounds way more complicated than it needs to be.


Before leds, knew lots of guys who started their plants at 10 hrs on, said they flowered harder and faster. What does DLI say is best for flowering phase?


There are some here that do go to 10/14 after flower is well set. I did that last grow where i adjusted an hour at every several days to get to 10/14 untill harvest. Do t k ow how responsible it was but i did have a hell of a harvest.


I hey @Dr-Atomic I’ve been using far red at lights off and again at lights on during the flowering stage to help increase yield. I like what I got last grow.

Studies have found that plants that were grown with the right amount of red light during flowering resulted in bigger, fuller plants with higher cannabinoid percentages. This is because a plant’s photosynthesis truly peaks during this much red light exposure, helping the plant to flourish.



Since I’m experimenting anyway this run I think I’m going to try this. It seems reasonable they could use a slightly longer day and still flower. I’ll probably turn the lights off for one day to start the flower. Then 7 days of 12/12. Then 13/11 till done.

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I also added a 100W UVA light as well that also during this time.

Have fun with it let us know if you notice any difference. Far red at the end of the cycle puts them to sleep faster.

I have been doing the same with far-red for several years. Excellent results.

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If you mean infrared I did something like that back in the day when I was using fluorescents. I had a line of 8 large clear glass incandescents down the middle. I made four completely adjustable arrays. Each one had four 4 ft. double lamp fixtures. That’s 32 four foot lamps. It was cheaper to do this than fluorescent grow lamps. Even with all those light fixtures the plants look somewhat sparse to me but the bud was outrageously good. I’ve only smoked a couple things that were better in all these years.

This is around 1980

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I’ve thought about adding far red. Where do you all get your far red lights? Looking for best bang for the buck and not too concerned about price.

@dbrn32 Do you know if HLG’s QB3 Far Red modules are effective and how would you go about finding a driver to run them? I have no problem drilling the holes necessary to mount them to a heat sink and running power to them, but I have no idea how many of these you would use for a single plant (they look really small) or what driver you would use to power them. Can you help? Are there other products that are effective at delivering far red to a grow that you could recommend?

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I got my three far-red bars from RapidLED. They require a regular power supply (12 V I think) which can be purchased along with the light bars. I have not looked into this sort of stuff for about four years so my sense of price is not current.

I purchased the power supply from RapidLED plus splitters to run all three on the same power module.


Did you mount these on an aluminum heat sink, or something else? I see that they only use 7 watts each, so I can’t imagine heat is any problem at all.


The far-red LED bars that I purchased come mounted on a heatsink. I just added a tab at each end and mounted them to the frame that hold my COB’s and ChiLED’s.

Here is a photo from the top:

The far-red bar is mounted to the underside of the long heatsink that you see.


Thanks. Appreciate the detail.


I did 2 boards @16 watts added to one of my main lights.
Ran 13-11 last run and seemed fine. I had so many other problems I don’t know if I benefited.

If ilgm is out again I think I have 2 more I’d let ya get :face_with_peeking_eye::green_heart:


Are those the HLG QB3 modules?


Yes sir