11/13? 10/14? will plants flower well with these light schedules?

Discussion in 'General Marijuana Growing' started by darkhelmut, Mar 14, 2009.


    darkhelmut Active Member

    Just started flowering. I know plants need 12 hours of dark to start flowering, and that it's the 12 hours of dark that keep them flowering. In nature, they must surely, at some point, receive more than 12 hours of dark (because once the natural light cycle shifts at the equinox the nights get longer). Is it ok to replicate that indoors, to save power? Can I put my plants on a 10 on, 14 off or 11 on, 13 off schedule?

    homegrown2009 Active Member

    just stick ith the 12/12 but you can if you wanted tojust make the light on 12 or 13 hours not elevn

    Sexologist420 Well-Known Member

    You can if you want...however doing so will cut your flowering time and reduce yields. The opposite is true of 13 on/11 off and 14/10 on/off. Dark time produces a hormone that triggers and controls flowering. The more dark time the more of that chemical is produced thus determining flowering time. This is why if you give your girls 48 hours of darkness before harvest they will swell up and create more resin and pistils. I dont really know how to explain it in a scientific way, I just know how to put it in lamens terms. Im sure some OG will explain it better and more scientifically

    Hope this helps,
    smoke and coke

    smoke and coke Well-Known Member

    yes you can but you will have a reduction in yeild. i would stick to the 12/12 because for the extra hour or 2 with no lights is only a few pennies a day saved versus more yeild that will pay you back in the long run. IMO.

    ganjaluvr Well-Known Member

    When flowering the plant indoors, 12 hours light and 12 hours dark is the standard lighting cycle during the flowering phase. However, 13 hours light and 11 hours dark will increase flower size (larger yield) while still allowing the plant to flower. But this will lengthen the time needed to harvest the crop.
    An extended period of darkness can also be substituted for the standard 12-12 cycle. 11 hours light and 13 hours dark will reduce the time needed for the crop to mature and harvest, but it will also reduce the size of the crop.

    I currently have my two Nirvana 'Ice' plants, they're both currently on a 11/13 cycle.. but tomorrow is the end of week #2 flowering, and the start of week #3 flowering. And starting in the morning, I'm switching my lights down further.. to a 10/14 schedule until its time to harvest.

    Hope my input helped you out some.


    ruudong Active Member

    The most common and basic cycle to set your high pressure sodium lights on for marijuana flowering is the 12 on 12 off cycle. This 12 hour light cycle is the maximum amount of light you should ever give your marijuana plants when they are in the flowering stage, producing marijuana buds. Anything more than 12 hours of light will signal the plant to continue growing in the vegetative stage, not allowing the plant to bloom and flower buds.
    This advanced light cycle will save you time, money and increase overall production by up to 50%. This flowering light cycle is based on plants that are a 9 week flowering strain. Heres a breakdown of how you should set your timers for your HPS lights in your flowering or bud room:

    Weeks 1-2: Set your timer for 11 hours on and 13 hours off.
    Weeks 3-4: Set your timer for 10.5 hours on and 13.5 hours off.
    Weeks 5-6: Set timers on for 10 hours and off for 14 hours.
    Weeks 7-8: 9.5 hours on and 14.5 hours off.
    Week 9: set timers to 9 hours on and 15 hours off. this is the final week of flowering and you should be “flushing” your plants to remove all chemicals and nutrients from the roots.

    hope that answers your question

    edit lol just noticed how long ago this post was

    NietzscheKeen Well-Known Member

    I'm wondering about this questions as well as I've planted some plants outdoors and they have begun to flower. I thought 13.5/10.5 hours of light/darkness would be enough to prevent flowering. I guess I was wrong. What can I expect? Any Advice? I live at 30 degrees lat. so I will only get 14/10 at best.

    joeljrscr New Member

    ok i have few plants indoors that are on a 12.5 hours of darkness and 11.5 of light. they have been flowering for 1 month. i am moving and can not carry them with me. my time zone is central and its 13.5 hours of daylight outside and counting down, if i put them outside will it hurt them or switch them to veggie? or will they be ok and keep flowering?

    tarks Active Member

    I just go 10/14. One reason is because i'm cheap and the other is they are still getting 10 hours. It's more then they get if they were in the sun , they won't notice 2 hours when they started off at 24/0

    Pig4buzz Well-Known Member

    My time zone this season the longest day is middle of July. OF corse days getting shorter eac day after. 14:34 is he longest day. The few outdoor grows I grew begin to flower 1st of August From this time the to end of September the daylight is still over 12 hours of daylight and flowering is over 10-15 days before. (Mid-sept). This growing outdoors completely. 2ls to 4ls was common. As long as your days are getting shorter(daylight) they should flower. Not sure about 12/12 areas how they work. My zone they never are 12/12 during flowering
    Dr. Who

    Dr. Who Well-Known Member

    I have never seen this much BULL SHIT about lighting times here as in this thread of answers!

    There ARE strains that will flower at 14 on and 10 off! I don't suggest you try that!
    The light spectrum the plant is exposed to has effect too.

    The 12/12 time is simply an accepted guide line for positive success! I find that MY plants are MORE stable and I have better results with no more then 11.5/12.5 and I usually run 11/13.....I don't have the "Herming" problems at ALL this way! My yield is NOT reduced in any measurable way. In fact I have have my best yields with 11/13!

    The act of reducing lights on times will signal slow/stubborn bloomers to "speed up" long blooming plants that seem stuck late in bloom to actually ripen and finish.....I've done that with some REAL fussy Sativa land races from SE Asia.....That would be like a 10/14 and these equatorial Sativa's ARE run at 12/12 till that point. Employing a "slow, paced reduction" in on times, later in bloom on these strains works quite well.....Just like nature does!

    There are other methods to increase "on" times by manipulating the spectrum of light exposed at certain times, for certain lengths of time. That involves using very particular nanometer band LED's in the 730nm band and I experimented with that. You could then run about 13.5/10.5 to 14/10 and it did increase yields BUT, for the cost of the extra electricity used and the cost of the actual LED set. I found that as NOT cost effective to the minor yield increase!

    There is another time reduction theory that involves reducing to as low as 6/18. This DOES reduce yields to around a 25% loss!
    Once you get below 10/14 you do get measurable yield loss, fast and on a bell curve......Like I said. lowering to 10/14 is done LATE in bloom to speed up only stubborn strains in my book....

    There you are, simple, factual answers.
    Dr. Who

    Dr. Who Well-Known Member

    I just got duped into a 7 YEAR OLD THREAD!

    Hope this thread helps someone!

    Pig4buzz Well-Known Member

    What happen if you veg 24/0 indoor of course, then put your plants outdoors when the daylight is say 12/12 and the days get longer each day? Up to 14.5 hrs before getting shorter. Do the plants flower or stay in bloom? Or go back to veg due to increase of daylight over the 6-8 week flower stage? Complete flower cycle?, turn into hermi?
    Dr. Who

    Dr. Who Well-Known Member

    I have never put out plants that did not remain in veg. Lengthening days tend to keep the plant in veg. ...I live in MI and your limited by temps as to when you set them out. They won't start to bloom until late July, early Aug.
    If you can put them out early.....They would reveg but, that burns time and plant energy....Here the bloom come a little late so strains that finish fast or are frost resistant work best.....

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