24 Hour Light Cycle After Flowering Begins?

Discussion in 'Indoor Growing' started by pseudoscience, May 9, 2008.


Do you think this would work to get larger buds?

  1. Yes

    5 vote(s)
  2. No

    34 vote(s)
  1. pseudoscience

    pseudoscience Registered

    I was wondering if this might get larger buds.

    • normal vegetative light cycle (24 hours)
    • introduce flowering light cycle until flowering BEGINS
    • revert to 24 hour lighting

    Based on what I know about other plants, once flowering has begun and florigen is coming out of induced leaves no matter what happens to the light cycle, flowering will continue. I also am assuming that a longer light cycle (like that in vegetative) fixes more photosynthates that are being pumped into the buds. Any input would be appreciated.
  2. GreenDestiny

    GreenDestiny Registered+

    Sorry, it wouldn't work. It is very sensitive to the amount of light it gets or does not get. MJ depends on the right ratio of light/dark hours for optimum flowering, which is usually 12/12. It's during the dark hours when all kinds of good things happen as a result of the stored energy it receives during the light hours. You could experiment by slightly skewing the ratio to see if it has any benefits for you, but 12/12 is the standard for MJ flowering. And even at the end of the flowering stage a couple days of total darkness can help by forcing the plant to put all of its last bits of stored energy into it, squeezing in every last drop of resinous THC it can.... or something like that.

    Although, I have no idea how any of this applies if you have one of the autoflowering strains..... never bothered to research those kinds.
    Last edited: May 9, 2008
  3. Fencewalker

    Fencewalker Registered+

    Agreed. What you know of other plants doesn't apply to cannabis. If you revert back to 24 hour light the plant will revert back to it's vegetative state.
  4. grey1223

    grey1223 Registered+

    No Way. I've had accidents where my plants received a little light while flowering. Once they are in the 4th or 5th week of flowering they are immune to temporary light intrusions but before that time it my delay maturation.
  5. pseudoscience

    pseudoscience Registered

    Thanks, this is the answer I think I was looking for. I should have asked specifically about how long after flowering began should one wait before a lightang can occure. It makes sense that it may take 4 or 5 weeks of flowering for enough florigen to be present in the plant for flowering not to be interupted. Based on what you are saying I may experiment with a longer photoperiod towards the end of flowering.
  6. Fencewalker

    Fencewalker Registered+

    I agree with that. But that wasn't what the first post seemed to be saying.
    The way that reads, it would be a bad idea. ;)
  7. pseudoscience

    pseudoscience Registered

    A temporary light intrusion should not be different than an extended light cycle. The plant can pump the photosynthates it makes in the day period--it does not need dark to do that. The only purpose of a dark cycle should be to signal for flowering. I don't think GreenDestiny completely understands how plants make, store, and transfer energy. In fact, I am pretty sure we could do something like keeping blue light on the plant all the time--it is far outside the range (red and far red) that have an effect on converting the two forms of phytochrome (a cis/trans thing) back and forth. I am going to consult my plant physiolgy book over the next few days while studying for finals and see if I can find out more information on this. I consulted with a professor at my university (a physiologist) who says that flowering should not be able to be stopped once in progress regaurdless of the light cycle. I'll be posting a more in depth reason for this and possibly a better hypothesis to test.
  8. GreenDestiny

    GreenDestiny Registered+

    Well from what I've read over the years it's during the dark hours of flowering when THC production is at its highest.

    Also its the extended hours of darkness that increases the flowering hormone to signal it to begin flowering. Keeping the same light schedule through most of flowering is important so it won't be stressed, but nearing the last few weeks you can slightly adjust it for more or less light to speed up or slow down flowering time.

    Here's some extra info about flowering, I don't have any copies of growing manuals anymore but found some stuff at http://www.a1b2c3.com/drugs/mjgrow4a.htm :

    and here another bit from http://www.skunked.co.uk/articles/growing-marijuana-05.htm :

    So in a way, yeah it does use the stored energy from the light periods so that during the dark hours the flowering hormone is at its peak each night, which is a result of the dark periods. I swear I'm not crazy, doesn't this all sound right?
  9. pseudoscience

    pseudoscience Registered

    It's all about the form of Phytochrome

    The information about the hormone is wrong. Phytochrome has two forms. It is a pigment that initiates the release of a hormone when it transforms from Pr to Pfr--this stand for red light and far red light. Far red light (what is seen mostly by the plant just before night) converts the Pr (this is the inactive form) to the active Pfr form. This form of the pigment enter the nucleus and tells it to code for Florigen (a protein that is a hormone just recently discovered). Red light converts the active form of Phytocrome (Pfr) to the inactive form, Pr. This process takes a while for enough Phytocrome to enter the nucleus and cause Florigen to be created--this is why the dark cycle is required. Thus dark periods are required until enough Florigen has built up. This is what that guide at a1b2c3 eluded to--however I do not think it was written with the knowledge of the newest science.
  10. GreenDestiny

    GreenDestiny Registered+

    Ah, ok... well most of the cannabis grow guides out there are written with sorta out-dated info with no mention of how phytochrome works... that's some interesting stuff, now that I know a bit about it, I can look up more info.

    Seems to come into better use when using LED's since they can put out certain wavelengths for the red (660 nm) and far red (730 nm). So then I guess proper manipulation of that stuff could yeild better results... all stuff way too technical for me to ever mess with.

    anyways, thanks for letting me know about phytochrome!
  11. cture

    cture Registered+

    I'm glad to see you around, pseudoscience could you check out the spectra I have in my signature an scientifically critisize it.
    Best regards
  12. Orzy

    Orzy Registered+

    Cannabis can be put back into veg at any time during it's flowering cycle. It's called reveging and you do it by changing the plant's light cycle to 24 hours a day. Flowering halts, and depending on the strain new vegetative growth will appear in about a month.
    • Like Like x 1
  13. Fencewalker

    Fencewalker Registered+

    But it is different. Ask anybody who's timer has broke and the plant reverted back to vegetation before they realized it. I personally have had this happen with a Mazar grow.
    Looking forward to it.
    The professor is wrong, concerning cannabis. <shrug>
    Ding! Ding! Ding! We have a winner. :Rasta:
  14. Fencewalker

    Fencewalker Registered+

    Double post...Sorry.
  15. pseudoscience

    pseudoscience Registered

    Here is some info. Cannabis is a short day plant (SDP).

    Attached Files:

  16. GreenDestiny

    GreenDestiny Registered+

    yep, short day / long night plant :)
    I guess that's why giving longer dark periods in flowering will speed up the process...
    mmmm I can feel the puzzle pieces in my brain fitting together
  17. bugmenot2

    bugmenot2 Registered+

    wouldnt it be ok to use a far red light? You said this is about 720nm, well thats nearly infra-red. If you illuminated the plants in this light throughout the "night" then the Pfr that's converted back to Pr by the process of creating florigen could be continuously converted back to Pfr by the far red light, possibly speeding up flowering. Does this make sense? I'm not an expert, but this makes sense to me from what has been said here (unless I got the wrong idea).
  18. joedirte

    joedirte Registered+

    honestly dude, why dont you just try it and maybe well all learn something.
  19. Rusty Trichome

    Rusty Trichome Registered+

    Unless you're asking about auto-flower strains, it doesn't work that way with cannabis. The ladies will switch back to vegging. Period.
  20. cornish_dope

    cornish_dope Registered+

    I will not say this is completely true but I'm pretty sure it is.

    The purpose of the THC gland is to protect the seed pods from ultra violet rays, therefore the more ultraviolet the more resin glands that need to be produced, I know a few people who will add in an ultraviolet light and it does seem to increase potency a little ( as far as we can tell).

    You can also drop the lights to 10/14 which according some grow guides will speed up flowering but reduce yields slightly.

    But the most important thing I should mention is: the conventional methods work, giving us potent stinky bud, it always works it's tried and tested why fuck with it?

    If it aint broke don't fix it.

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