The far red thread

Discussion in 'LED and other Lighting' started by Rahz, Apr 14, 2015.


    Fastslappy Well-Known Member

    Far Red ,15 minutes before after worked well for me at 12 hrs

    nachooo Well-Known Member

    You are confused ,when we talk about the 2 hours time ,we are talking that when Fr is not present at the end of daylight time (your 15 minutes), the plant last two hours to be ready to sleep, this only happens in indoor conditions without the addition of Fr

    nachooo Well-Known Member

    In my case I do not use Fr to add more light hours.. I have done it succesfully, but now I prefer to use it just for accelerate maturation time in sativas mostly. Is more efficient to use it this way in my opinion
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    InTheValley Well-Known Member

    They say 730nm cancels out 660, and 660 cancels out 730. So id imagine, for the most benefits from it, Its either or.

    So using a incandescent bulb, which has both, would do nothing.? Thats what i gathered from it.

    The plant senses a LEVEL of hormones of both p and pr, night lengths give it time for conversion to and fro the other.

    When it hits a level, it flowers. ( the level being NIGHTTIME ACCUMULATION OF P)
    the sun always produces 730nm, but its about the distribution time thru the night, that either makes it a short or long period flower.

    Whats important is understanding that it knocks off 2 hours, basically because it takes the natural process that long to SWITCH over.

    I wish there was a visual of the process thru timelapse of what really goes on at night.
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    NewBKind Active Member

    Just grabbed these cree initiators and rapidled 4x4 canopy substrate with 3x rails.
    Now i Just need a good led controller to wrap up this cob array. Anyone know of a good cheap way to time the initiators? I'm already over $1000 into this 4x4 cob rig now that I've added these I can't afford a bluefish just yet

    Attached Files:


    Danielson999 Well-Known Member

    Is that light capable of running the 730nm and photo red independently? If not, it's used for emerson effect and not as an initiator since flower initiation is strictly 730nm by itself. It seems your light is simply supplemental red but if you can shut the photo red off and only run the 730nm at lights out you'll be golden. Even better would be running the photo red at wake up before everything else comes on.

    NewBKind Active Member

    I can run them separate, i was going to run the photo red at wakeup and far red for 15 minutes at lights out

    NewBKind Active Member

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    hydrohaz Member

    So it shortens the flowering period but will it lower yield?

    Rusher Well-Known Member

    I regulary pull 1.5 to 2oz in a 42 to 49 day window with most strains. I run the 730nm for 5 minutes before lights out and 10 more minutes after lights out. I'm using only 380W of 3500k COB lights, hence the 2oz plant as opposed to some of the monsters @GroErr pulls.

    I'm in 9sqft harvesting 1 plant every two weeks.

    I don't think the yields are reduced much, if at all. Just a faster timeline, in my opinion.
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    burnpile Well-Known Member

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    Randomblame Well-Known Member

    Nope! If you do it right you can shortening the flower cycle while getting even better yields. Imagine a 13.5/10.5h regime with 5 minutes EOD far-red treatment.
    The light hours lost by the shortened flower period are compensated by the longer days (13-14h). Most strains tolerate 13.5-14h light with far-red treatment at the end of the day(EOD).
    Try to give ~4000μmoles per square meter to switch the plants into sleepmode. More could already trigger SAS(streching, bigger leaves, ...).
    With 10w of 730nm that's about 5 minutes.

    (10w x ~40% eff.(eg. 7 XP-E @700mA) = 4PAR/w x 3.5μmol/J (QER, cherrypicked from Luminus calculator)= ~14μmol/s.
    4000μmol : 14μmol/s = 285seconds or ~ 5minutes)
    Last edited: Jan 6, 2018

    GroErr Well-Known Member

    This is what I've been doing for a while. I also tried different cycles from 12.5/11.5 to what I'm running now at 11.5/12.5. I run the 660nm 12 minutes with 2 minutes overlap at the beginning and 730nm for 12 minutes at lights out. I have 3 phenos that I can pull at 49 days from flip in this config, no noticeable loss in yields and great quality. I noticed the most significant reduction in finish times when I went down to 11.5/12.5 with the initiators.

    A couple of bud shots at day 34 I grabbed earlier. The Fireballs can usually be pulled ~ day 49...

    Dream Ripper:
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    HideousPenguinBoy Well-Known Member

    When you did 11.5 of light with the far red it went faster? I would've thought doing MORE light a la 13-14 hours of light would have sped that up/given bigger buds?
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    GroErr Well-Known Member

    That was my thought going into testing. I ran 2-3 rounds each in 1/2 hour increments starting at 12.5/11.5, down to 11.5/12.5. The longest finish times were at 12.5/11.5, really good yields as you would think, but longer finish, by up to 10 days. I used known clones to get consistent reads on finish times.

    I don't look at it as one method is better than the other, more interested in knowing what they each have to offer. I prefer faster finish times, more flips, multiple strains, more variety. The faster cycles with more variety fit well into that style of growing.
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    burnpile Well-Known Member

    I've had mine at 11/13 this run, looks really good. I think the 11 hrs really makes them think its getting late in the season, time to pour on the sh...

    Tonight all the sk #1 are bending over, tied a lot up to supports. I need to get a better support system, its really nice without any until now.
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    hydrohaz Member

    Thanks guys think il grab the growmau5 far red puck

    HideousPenguinBoy Well-Known Member

    I would love to know the numbers to see what the weight gain was for the extra days and such. It's a damn cool idea and I'm way into understanding how the plants work with the "extra 1.75 hours of sleep" and also with the differing day/night lengths. Hormones and PPFD absorbed in a day and changing cycles to mimic seasons. I want it all and I'm surprised it's not info already out there!
    GroErr likes this.

    GroErr Well-Known Member

    I didn't have enough controls to get real numbers for weight. My focus with the tests were finish times, secondary was balancing finish time vs. yield. I could tell I got a little more weight overall with the longer run on the control clones but incremental, not like it was a huge bump. If there was a 10% difference I'd be surprised.

    Consider this though, let's say you get 10% more weight by running them in a longer lights-on environment. But now the finish times go 10 days longer. Is there really any gain?

    Let's look at this in numbers and practical terms with harvests in a year:
    Harvests at 63 days (365/63) = 5.80
    Harvests at 56 days (365/56) = 6.52
    Harvests at 49 days (365/49) = 7.45

    Now let's say that in my case I pull an average of 2 lbs./harvest.
    Let's also allow that I'll lose 5% in yield per week to allow for slightly less yield as the finish times are reduced.

    908 grams x 5.80 = 5,266g/188.1 oz./11.75 lbs in a year/14.42g/day
    863 grams x 6.52 = 5627g/201.0 oz./12.56 lbs. in a year/15.42g/day
    820 grams x 7.45 = 6109g/218.2 oz/13.64 lbs. in a year/16.74g/day

    Net effect is an increase in yield, not loss. Unless you were gaining or losing greater than 15-20% per harvest, the numbers are better over a year by simply reducing your harvest times.

    tomate Well-Known Member

    Could you tell us about your setup? Lights used, wattage, distance to canopy and grow space?
    I'm asking because it would be good to know which amount of light your plants are getting (DLI).

    My guess is that a DLI of ~35 mol/d is what we should be aiming at. 35 mol/d equals a PPFD of around 800 µmols/s*m² at 12/12.
    Now the question is, wouldn't it be beneficial to increase the intensity (ppfd) if you run 11/13 for example to keep the DLI at the same level in the hope that you benefit from the significant shorter flowering time but without losing the extra yield you would get whit a longer light cycle?
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