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12-1 lighting schedule, has anyone actually tried this?

Discussion in 'General Marijuana Growing' started by LILBSDAD, Jul 9, 2011.


    reverof Active Member

    I know one person that does a similar grow as described in the 2nd post of this thread, quoting (i forget the name now).... Only 1 difference and I dont know why this would be any difference then the stated 5.5 off 1 on 5.5 off, but he runs 14 hours on and 10 off in veg and runs exactly 13 off 11 on for flowering. No joke his veg plants in 4 weeks are normally 20-24" tall. In comparison I gave him a germinated then planted seed in a 1gal pot as I did for my seeds of ICE, exact same time, both of us use T5 for veg lighting, the plant I gave him in exact same time was almost exactly 5.5 inches taller than the tallest one I had.

    Only reason I don't run the same light schedule is I run autos in my veg rom quite often so I run a 18/6 schedule.

    LILBSDAD Well-Known Member


    420forme Active Member

    Looks great, I like that someone is trying this method. I brought it up a couple weeks ago and no one got then either. You get the same if not better growth from less electricity, and less wear on your equipment. That doesn't make sense to people? Do you think commerical rose growers veg for 18-24 hours a day? No, if they did a rose would cost $50. This is a common practice in commercial growing.
    As far as the flowering cycle is concerned I'm a little less sure. While a little extra dark my increase trich production I think it would decrease overall size.

    skunkd0c Well-Known Member

    i find these lighting experiments interesting i havent been brave enough to conduct any myself yet .. as overall there is very little reliable information on photo period experiments ..i would like others to risk their plants first before i am willing to try it

    i have read about keeping plants in veg by interrupting the dark period some similar info here http://mjgrowers.com/book_what_exper1.htm

    also from what i read, during flower giving longer days could be of benefit, which seems to make sense .. the more light the plant can receive and still stay in flower, the overall more energy the plant is receiving to produce more bud
    as opposed to the opposite idea that reducing the 12/12 would be of benefit

    since the critical darkness period for some strains is only 9.5 to 10 hours, it might be of benefit to flower these plants with a 14 hour to 14.5 hour on period ..these 2 extra hours work out to an extra day per week of light increasing the overall light energy the plant receives

    there is another idea that you can increase the overall photo period to over 24 hours by giving 21 hour on periods but still give 12 hour off periods
    you need a 7day timer for this to set different times daily .. this idea seemed a bit wacky to me .. but interesting none the less :)

    snew Well-Known Member

    I started "Gas Lantern" technique for veg light about 2 weeks ago. After 1 1/2 weeks at 24 to start seedlings and clones. I now have those seedlings and a few more clones under 12-5.5-1-5.5 . The plant s seem healthy especially since they were all exposed to spider mites and had to be treated early. The believe my node development is tighter than previously. I already run my flower room at 11-13 since Jilly Bean seem to flower much better for me at 11-13 than at 12-12. I'm not sure as to weather I will use the decreasing flower light hours or not.

    I don't think I've seen these links on this thread, you'll enjoy if you have not read them.

    http://www.treatingyourself.com/treatingyourself/images/issues/pdfs/issue28.pdf, page 84

    http://www.treatingyourself.com/treatingyourself/images/issues/pdfs/issue25.pdf, page 77

    So far I found this to be right on target.

    BobCajun Well-Known Member

    Why even on for a full hour in the middle of the dark period when all you need is a few seconds to prevent flowering completely? You'd save even more power then. This has been known for a long time, that even an incandescent bulb flashed on for a few seconds prevents flowering. I know most timers have a minimum 1/2 hour increments, so I guess it would have to be 1/2 hour on. How great a grower can that guy be if he didn't even know how little light is required to prevent flowering? I would be worried about herming due to weird photoperiod though.

    I tried 3 on 3 off, repeated for 24 hours, and I got quite a few herm flowers when I went to 12/12. I tried that because I read a study that showed that a 1-3 hour dark period in the middle of the light period increases growth significantly (this was in tomatoes, not Cannabis) over that of steady light, meaning that if the plant was getting say 13 hours of light per day that it grew a lot more with 5 on 3 off 5 on than a steady 13. That is because the leaves get saturated with light after a few hours and photosynthesis slows down. The 1-3 hours of darkness desaturates the leaves and when the light returns they grow a lot faster again. It could be that Cannabis doesn't saturate like that, because it's a C4 plant instead of C3. Anyway, I figured it might be even better if I gave them repeated cycles but maybe I should have only used one 1-3 hour dark period. My plants did grow like crazy with the 3 on 3 off cycle, but I got a lot of herm flowers on the plants later. Could have been the plants themselves I guess, it was a Northern Lights grown from seed.

    It's something an experimenter could try for themselves. The study showed that 1 hour off gave the greatest boost but that 3 gave almost as much boost. After 3 it starts decreasing so it's actually less growth than steady light. I give them 23 on 1 off for veg now, and it seems to be working well. I figure the 1 hour off is probably better than continuous light. It would desaturate them and also give the plants an actual day/night cycle. 24 on may cause stress. They probably do need at least a short dark period for normal metabolism. They perk right up after the 1 hour off.

    THENUMBER1022 Well-Known Member

    what about a twelve on, twelve off, with the off having moonlights? LED's....

    Has this been tried?

    snew Well-Known Member

    Not by me. I'm started using the technique because of summer heat issues. It seemed to be working so I've continued it.
    kevin murphy

    kevin murphy New Member


    LILBSDAD Well-Known Member

    Thanks Kevin. I started flowering 2 weeks ago and these things are HUGE now. Did 36 hrs dark then went to 11 on 13 off. I will be reducing to 10 1/2 on and 13 1/2 off starting tomorrow. I will be tying these beasts up tonight so I will try and take some pics.

    LILBSDAD Well-Known Member

    kevin murphy

    kevin murphy New Member

    looking real good mate..
    Matt Rize

    Matt Rize Hashmaster

    12/1 totally ruined my friends crop. mimicking nature is one thing. 12/1 is so far from nature that I don't know where to start. Days/nights revolve around a 24 hour period, in nature. All organisms have this cycle in there genes, the circadian rhythm. Reducing light and changing bulbs as plants mature to mimick fall is one thing, that makes sense and replicates nature. 12/1 is okay for vegging already rooted clones, horrible for mothers, horrible for seeds plants, and does not help flowering out at all.

    LILBSDAD Well-Known Member

    What happened to ruin his crop Matt? You have me worried now
    Matt Rize

    Matt Rize Hashmaster

    He did a side by side in two rooms and the 12/1 yielded crappy small buds.

    LILBSDAD Well-Known Member

    Ruh Roh, that's not good. I ran the back end of it on my flower cycle last time and the buds came out nice. I was a little off my usual average, but I also had some new strains that ended up really small. I'm glad you didn't say they hermed. Thanks for the input Matt
    Matt Rize and kevin murphy like this.

    vilify Well-Known Member

    i dont see the difference.

    as far as the comparison i have 2 master kush clones taken from the same plant, same height when taken. one grows faster than the other. happens all the time. cant credit this to a light cycle.

    LILBSDAD Well-Known Member

    I really am not concerned about which one grows faster, my main concern is heat issues with 18hrs on during veg. I may just use this during the veg cycle but I will see how it goes this time.

    Harrekin Well-Known Member

    I'll be sure to try this if I want sad looking stretched out plants...

    I always get a giggle from people who judge their growth rate by height.

    skunkushybrid01 Well-Known Member

    height is definitely not a good indicator of growth. real growth (cell division) is often shorter, stockier, hardier.... stretch (cell elongation) is the exact opposite.

    12/1 is insane... i'm not a follower of the circadian rhythm myself as in my opinion plants can adapt to a new rhythm fairly quickly... however i still cannot get my head around 12/1. a plant needs a certain amount of uninterrupted dark to flower... are we talking 12 hours of light here? i hope it isn't just one hour of light. LOL... you might as well just grow the plant in the dark if that is the case.

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