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Thread: 24 Hours Vs 18 hours veg

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    Default 24 Hours Vs 18 hours veg

    hey guys thought this my be of interest to some,a bit of info on 18 & 24 hour veg, as lot of people debate over which is best, im not saying either way which is 'best', as i feel what suits your needs is the 'best' option, just a lil info below as to why they dont 'need' a dark period

    24 Hours Vs 18 hours veg
    Most green plants are classified as either C3 or C4 which represents how carbon(C) is used during photosynthesis.

    C4 plants temporarily store carbon dioxide(CO2) over the dark period to use for photosynthesis during the day. C4 plants slow down photosynthesis once the stored CO2 is used up and they need to gather it from the air. Which is why trees slow down photosynthesis in the afternoon even though the sun is still bright. This does NOT apply to cannabis.

    C3 plants(cannabis/veggies) gather CO2 only during the light period when they are photosynthesizing. During the dark period these plants only use oxygen for their metabolic life processes. They don't uptake CO2, nor do they use it. As soon and as long as the light is on, C3 plants gather and use CO2 for photosynthesis.

    C3 plants also have the ability to use higher concentrations of CO2 than what is found in the air. If the light is bright enough and the plants have sufficient nutes, their growth rate will accelerate from it(2000ppm vs. 400ppm of CO2), which increases yield. They can do this continuously, without a dark period throughout the vegetative stage.

    The dark reaction is a process of photosynthesis that takes place in both darkness and light. It uses ATP and NADPH molecules that hold energy absorbed from light to break apart CO2 into it's base components. Because it's called a dark reaction and can occur in the dark, some people(Jorge) have said darkness is needed for this to occur. This Is Not So.

    Again people get a little obsessed with their plants needs & think of them the same as humans. People need rest, so plants must too. This is false as well. Light means growth. Scientifically. Although 18/6 will 'shock' your plants less when you switch to 12/12, it's a personal choice whether you would rather sacrifice a little growth for a quicker adjustment or less photo confusion. If you want to save money or energy that's a personal choice too. Do what you need to do to make your growing situation work.
    Last edited by Superjoint 420; 13-02-10 at 06:26 AM.

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  3. #2
    FZjb Guest

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    nice

    tho i did read some experiment they did (who-ever "they" are!) on light cycles and it showed that plants with 18 hours a day had the longest root systems while those at 24 hours a day had considerably less root Length.

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    nice post !!!

    good read and educational!!!

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    Quote Originally Posted by FZjb View Post
    nice

    tho i did read some experiment they did (who-ever "they" are!) on light cycles and it showed that plants with 18 hours a day had the longest root systems while those at 24 hours a day had considerably less root Length.
    interesting m8, i know usually MJ plants roots grow quite deep given the chance

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    Quote Originally Posted by meangreenmachine View Post
    nice post !!!

    good read and educational!!!
    thanks m8

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    I'v done light cycle experiments, all sorts of em, compared em all and personally i think the best veg cycle is 14/10 or if you plan on a long veg time 15/9, the more dark you give a plant in veg the faster it will grow, as long as the plant gets no more than 10hours of darkness it will not flower, after 3weeks veg with 14/10 your plant will be huge and be covered in preflowers if its kept healthy, this is just my opinion on light cycles, they grow/mature faster,kick into flower "A LOT" faster (1wk hairs and budsites form,2wks you got buds on your plants) and saves money on electric, but everyone's got their personal preferences eh

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    Quote Originally Posted by Eddie1z View Post
    I'v done light cycle experiments, all sorts of em, compared em all and personally i think the best veg cycle is 14/10 or if you plan on a long veg time 15/9, the more dark you give a plant in veg the faster it will grow, as long as the plant gets no more than 10hours of darkness it will not flower, after 3weeks veg with 14/10 your plant will be huge and be covered in preflowers if its kept healthy, this is just my opinion on light cycles, they grow/mature faster,kick into flower "A LOT" faster (1wk hairs and budsites form,2wks you got buds on your plants) and saves money on electric, but everyone's got their personal preferences eh
    yea we all got our own ways lol

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    interesting. quite contradictory to the original post, and never heard of anyone growing with such a light cycle..

    would like to know if anyone else does this?

    Quote Originally Posted by Eddie1z View Post
    I'v done light cycle experiments, all sorts of em, compared em all and personally i think the best veg cycle is 14/10 or if you plan on a long veg time 15/9, the more dark you give a plant in veg the faster it will grow, as long as the plant gets no more than 10hours of darkness it will not flower, after 3weeks veg with 14/10 your plant will be huge and be covered in preflowers if its kept healthy, this is just my opinion on light cycles, they grow/mature faster,kick into flower "A LOT" faster (1wk hairs and budsites form,2wks you got buds on your plants) and saves money on electric, but everyone's got their personal preferences eh



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    i can understand why 14/10 would produce alot of groth because ur simulateing the days toward the end of the life cycle 18/6 being at the start of the life cycle e.g may/june/july wer as the 14/10 more towards aug/sep e.c.t. wich should trick the plant into thinkg its late in its cycle according to the light its recivieing making it grow more frantic 2 catch up and flower in time to polinate.
    Last edited by lowkey; 22-02-10 at 04:15 PM.
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    sounds about right m8 i prefer the 24/7 method did 20/4 last grow and my plants are allot biger this time round at the same time.

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