24 hour light vs. 18/6.

Discussion in 'Advanced Marijuana Cultivation' started by Sencha, Apr 27, 2010.


    Sencha Active Member

    Hey everyone. I've made my way through the various stages of research for my first indoor grow. However, I've seen that some people veg under 24 hour light and some under 18/6. Recently I spoke with a person from Cali who has published work in the Cannabible. He said that no MJ plant, UNDER ANY CIRCUMSTANCES, should ever be given 24 hour light. "It's only wasting electricity."

    Is this true? Thanks in advance.

    bobbyhopefeild Active Member

    ive tested both 24/0 and 18/6 , and concluded that 24/0 is better for those who have lots of cash to spend, dont care about the cost of electricity and are eager to harvest as FAST as possible
    however , 18/6 is a far better cycle as plants, like every other living organism needs a down period to recuperate, plants on 24/0 will grow slightly faster but the plants wont grow as half as fast as they did in the first 18 hours, therefore to an exstent the extra 6 hours is wasted as the extra light is used very inefficiently. go with 18/6
    Dogenzengi likes this.

    Nvr2Stond Well-Known Member

    I agree 100% here, I leave my 1000w hps on non stop and love the results.

    themistocles Well-Known Member

    go with 18/6 all living things need a down period, plus when would you foliar feed if the lights were always on?
    Dogenzengi likes this.

    SSHZ Well-Known Member

    I believe the extra 6 hours gives you about 10%-15% more gowth. Not worth it in my opinion..... And I like to let the room cool down some.
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    Sustainable420 Active Member

    Immitate nature.
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    sixstring2112 Well-Known Member

    24hr is the best way for me to keep things from flowering and bring flowering clones back to veg. also better to keep my temps steady for the little ones.18/6 for mothers works great for me.
    Aero guy and Dogenzengi like this.
    Mikey Hustle

    Mikey Hustle Well-Known Member

    My Kandy Kush flourishes in 24 hr light.

    Although, my Sleestack, Blueberry, LA Confidential, Azorian Nightmare, and LSD dont. These strains did better with the 6 hrs of sleep.
    Dogenzengi likes this.
    ink the world

    ink the world Well-Known Member

    I grow perpetual, I had 3 spaces, then got flooded out of our place. Veg room was 18/6, clone space was 24/7

    I now have 2 spaces and I use the same space for my clones and vegging. the lights stay on 24 hours so, they do seem to grow a tiny bit quicker.
    Dogenzengi likes this.

    Gardenmaster1 Member

    I agree that plants can only process 18 hours of light a day, any more is just wasting electricity.
    Dogenzengi likes this.

    azoo Active Member

    i give mine 15 /9
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    HookdOnChronics Well-Known Member

    If you actuall compare root growth in the 24/0 light schedual and the 18/6 light schedual you will see that you have a MUCH larger root mass in the 18/6 light schedual. And everyone knows what more roots means right..... :)

    I use to grow 24/0 in veg. Untill I campared the root growth of that plant to one of a plant of the same size and strain in 18/6. Just seeing the difference made up my mind for me... 18/6 ALWAYS!
    Dogenzengi likes this.

    zigzag6 Active Member

    Seedling - 24/0
    2 or 3 leaf sets - 18/6
    Flowering (whenever) - 12/12
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    JLH1983 Well-Known Member

    hey all....
    anybody experimented with "day" length?? ie. 20/6, or 24/6 for vegg....?

    also is it the shortened daylight or extended dark period that triggers flowering?-- ive pondered like a 14/12 or 16/12 to try for flowering... cant find any research on the subject-- or possible pros/cons?
    Dogenzengi likes this.

    HookdOnChronics Well-Known Member

    Dude.......... What world, or time zone are you living in to get 30 hours in a day? lol ;)
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    bob+marley Active Member

    thanks HookdOnChronics for pointing that out.

    i just laughed hysterically. I should really get out from behind this keyboard haha.
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    J.cun.Shallow Active Member

    I heard some guy say that in the flower cycle he leaves lights on for 36 hours and then 12 hour dark
    Dogenzengi likes this.

    Gardenmaster1 Member

    I have never tried it my self but I have heard that you can go 18/12 as the best cycle for flowering. It does not change yeild or potency, but a plant that takes 8 weeks to flower will be done in 6 weeks.

    First I am not sure where you could get a timer capable of this, and second think or the poor confused grower trying to figure out when to water, and foliage feed.....
    Dogenzengi likes this.

    CLOSETGROWTH Well-Known Member

    Ive been growing for over a decade, and recently went from 24 to 18..

    My roots are so much bigger now, and way more healthier foliage.

    Growth rate, about the same..

    Give your plants a break :)

    Let em sleep! ;-)
    Dogenzengi likes this.

    HookdOnChronics Well-Known Member

    THIS! I did the exact same, as you can see in my earlier post, with the exact same results..... It's true and if your reading this, and your vegging under 24/0, trust me..... It is WELL worth switching to 18/6./ I didn't even realize untill I tried it!...

    Hahaha, I was cracking up to dog! lol
    Dogenzengi likes this.

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