Light cycle cuts down Flowering Time?

Discussion in 'Advanced Techniques' started by GreenLeaf420, Jun 25, 2008.

  1. GreenLeaf420

    GreenLeaf420 Banned

    I was on a forum and reading an article that was stating that changing the light cycle you can cut back flowering time and increase Yields..

    If this is true it would be fantastic. I've read up on the Alternating Light Pattern Theory. Which people are claiming to also receive better results then all light's on.

    The article discussed a growers experiments with 18 hour light cycles, based on the theory that plants were most efficient at gathering light during only a portion of the 'day' cycle. I want to say that during veg, he used 14 on 6 off, and during flower he used 6 on 12 off.

    The grower claimed a 3 week shorter harvest cycle, with a 30-40% increase in yield.

    Something about this rang true to me, and I want to reread the article, anyone know what I'm talking about or where to find more info? I've tried google, and of course the respective search functions on each site I frequent, with no luck.

    Has anyone else Heard of this article?

    Thanks GL420:jointsmile::jointsmile::jointsmile:
    • Like Like x 1
  2. GreenLeaf420

    GreenLeaf420 Banned

    Has anoyone ever heard of such things???

    If this is true it would cut down on flower time!!!
  3. stinkyattic

    stinkyattic CultiModerVatorAtor

    It will shorten flower time but at the expense of yield per harvest and per plant.
    Try CO2 enrichment instead.
  4. GreenLeaf420

    GreenLeaf420 Banned

    Stink I already am using CO2 but the whole theory of going on a 18 Hr day with 6 on 12 off that is crazy. The CO2 will increase the yield but I never heard of it speeding up the flowering cycle. You have seen it or done it the hole 18 Hr day theory? I find it to be fascinating if it cut's back on flower time...

    Thanks for the info GL420:jointsmile::jointsmile::jointsmile:
  5. GreenDestiny

    GreenDestiny Registered+

    I found it...

    It's basically manipulating the circadian rhythm... It's assumed that since Earth has 24-hour days, all plants and animals are entrained to it. But in my opinion, not every plant or animal is created equal... 24 hours is just the average norm. Some things might do best with longer or shorter days...

    I found the article you were talking about:
    The source it references, , doesn't seem to work anymore but is still in Google's cache

    Too bad it says it gives the same yield... but doing it in less time with less power is still pretty awesome...


    Growing with an 18 hour Day/Night Cycle

    The Theory
    The theory behind the 18 hour Day/Night cycle is that during a normal 24 hour light cycle plants will usually achieve high growth rates peaking at 100% capacity during the first 50 - 60% of the day. The growth rates will then diminish rapidly and the last 20 - 30% of the day achieves minimal growth. So by reducing the length of the day we are triggering an increased growth mode where the growth rates are at their peak for the majority of the day. This effectively achieves a very fast growth cycle with full yield potential.

    NOTE: To achieve these incredible growth rates it is important to provide maximum light intensities and CO2 enriched conditions. The recommended lighting is 600W per square metre.

    The Cycles
    Vegetative Cycle - Lights ON 14 hours, Lights OFF 4 hours
    Flowering Cycle - Lights ON 6 hours, Lights OFF 12 hours

    The Benefits
    The growth acheived during an 18 hour cycle can be the equivalent to that acheived during a 24 hour cycle. So by running 18 hour cycles the same growth and yield can be acheived in 75% of the time.

    Reduced day lengths also mean reduced power consumption. Grow more and use less power. Who can argue with that?

    For example, an average crop grown from seed using a 24 hour day/night cycle will have a 4 weeks grow cycle and an 8 weeks flower cycle. This equates to 28 days @ 18 hours a day and 56 days @ 12 hours a day = 1176 hours of light over 12 weeks.

    An accellerated crop using an 18 hour day/night cycle will achieve the same yields using a 3 week grow cycle and a 6 week flower cycle. This equates to 21 days @ 14 hours a day and 42 days @ 6 hours a day = 546 hours of light over 9 weeks resulting in a 40% reduction in power consumption and a 25% reduction in crop time.
    Last edited: Jun 27, 2008
  6. GreenDestiny

    GreenDestiny Registered+

    If you use that method's principles and apply it to the photoperiod manipulation that's in the Grow FAQ, How do I manipulate the photoperiod for larger yields?, then you'd be one crazy weed growin sucka.

    I'm too tired to figure it out on my own right now to see if the numbers would work for modifying that photoperiod scheme into the 18hr cycle... If it can be done, then I hope someone tries it. If not, just try the 18hr cycle by itself.
  7. GreenLeaf420

    GreenLeaf420 Banned

    So I guess it cuts down on time but like STINK said it probably cuts down the yield.

    20-30% of the end light is only absorbed but it is absorbed and that probably effects yields. Every other article I'm reading is related to a new timer they are selling.

    Has anyone tried this?
  8. JewBilly

    JewBilly Registered

    Growing with an 18 hour Day/Night Cycle

    There is a thread at Effects of different photoperiods on flowering. - International Cannagraphic Magazine Forums with an experienced grower, Blckbrd, using 24/7 and 7/12 photoperiods. He claims identical results with less power consumption and 25% lest time. "I really do it to just speed up the harvest time. I like genetics that take 70+ days to flower and the 7/12 cycle is about 24% less time ( over two weeks less ) of flowering time. The finished product is huge, dense, and true to the genetic expectation. I have not observed any detriment at all."
  9. MistaJ

    MistaJ Registered+

    Has anyone on this board experimented with time periods such as these?
  10. low_rdr

    low_rdr Registered+

    I'm starting my next vegged plant at 7/12 - Its a clone from a plant that was ready in 7 weeks (pineapple express) - This one has been vegged for 6 weeks and is 24" from base to tip (although LST'd) and currently has about 40 nodes.

    It'll be a week before I put it into flower.
  11. low_rdr

    low_rdr Registered+


    This is INSANE! Not only did I already write this post and apparently pushed cancel - But the new light schedule is AMAZING with the plants. I wish I had taken before/after shots but it slipped my mind, I figured it would take a long time to see results... It doesn't.

    I went with 6 on, 12 off - Then on two consecutive days its 6 on 18 off. I'm using a brinks timer that allows 6 different settings/days so 5 are set for 6/12 and two are combined at 6/18.

    Now.. I said that I was vegging the pineapple for at least another week because my flowering cabinet is full and a good portion of them had decent buds, but purely clear trichomes... They'd been that way for about a week, so I figured I had a good week or two left.

    After 2 days, the hairs are 40% red, trichomes are 70% cloudy and 20% amber.... I'm VERY impressed. The only other change so far has been the addition of pop/rock music during lights on.

    Benefits: Faster budding period - Less power consumption, and for some reason, happy as hell plants. I've got a powerbud in there that has a top cola that is absolutely HUGE, and it's gotten bigger in the past two days. This bud is the size of a solocup in width and a can of monster in height - My previous buds were the size of pill bottles, so this is a BIG increase. The new lighting is only partially to blame, but it is finishing much faster!

    My advice to you, stop what your doing, and change your light schedule. If you want to wait until my pineapple express finishes, that's fine - But I'm thinking my pineapple will be done in 5-6 weeks vs 7 that it took to finish last time


    Oh, the negatives: The timer is a pain in the ass to setup. Also, since the lights change times each day, its hard to get a set 'inspection' schedule - I haven't actually had a peek at the girls during lights on yet, won't be until tonight.
    • Like Like x 1
  12. Buggy

    Buggy Registered+

    Low - how were the results, and how much do you think the lighting contributed?

    Anyone here have enough space for two small grow areas to test this? Start with 2-4 girls in each with the EXACT same set up (lights/space/temp/humidity/ferts/water/air flow/co2/etc) but do one with the norm 24/0 or 18/6 then 7/12 on the one, with the other being the new suggested lighting. I'd like to see the difference in veg first, and then flower second. I can understand the flowering in many ways to be increased with the shorter light periods - most plants don't get concentrated light for THAT long each day anyways.

    Hmmm - any studies that people are aware of for the ideal number of hours of direct sunlight the plants need outdoors? Roses prefer 6+ although some do very well with 4+ and then light or total shade the rest of the day. Some plants only like 2-4 hours direct at most. What about cannabis? What is this plant's preferred light intensity? That could signal how long they really need lights on at a time.

    Also, does it matter that much to the veg time if it's 12/6 or 16/2 or 24/0? There are some people that do straight 12/12 for seedlings even, so... I don't really know. Anyone?
  13. Jaybake 75

    Jaybake 75 Registered

    Ok i have a question say in 3weeks in flowing on standerd 12/12 light cycle. Is it safe to switch from 12/12 to 6/12 cycle without stressing the plants?
  14. emilya

    emilya Future Dispensary Owner

    absolutely not, and besides that... what is a 6/12 cycle... and what did you do with the left over 6 hours?
  15. Buck Rogers420

    Buck Rogers420 Registered+

    if the first 6 hours on are the most perdective, what would happen if you ran your flowering time at 6 on,6 off, 6 on, 6 off?
    • Funny Funny x 2
  16. emilya

    emilya Future Dispensary Owner

    your plants would stay in veg, very confused and angry.
    • Agree Agree x 2
  17. Buck Rogers420

    Buck Rogers420 Registered+

    even if you went straight from 6/18 TO 6/6/6/6 ?
    • Funny Funny x 2
    • Dumb Dumb x 1
  18. emilya

    emilya Future Dispensary Owner

    even if
    • Funny Funny x 1
  19. Weezard

    Weezard Registered+

    Theoretically as long as the dark time is longer than the light time cannabis will flower 6 on, 7 off.
    You need to read about photoperiodicity.
    Then sit and think for a while.
    In theory, theory and practice are the same.
    In practice, they are not.

    Screwing with circadian rhythms is a good way to get pollen from a female, it is risky business.
    You will note that this thread is quite old and the original poster
    Low_rdr has not been back to show positive result since 2013.
    This thread died for good reason.

    All that said, nobody knows everything.
    Might be fun to set up an experimental, side by side grow to test odd light cycles and share your results with us.

    • Winner Winner x 1
  20. Buck Rogers420

    Buck Rogers420 Registered+

    so theoretically, you could go 5on, 7off, 5on,7off and still have 2 major growth sperts a day. if it doesn't herm on you.

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