How long do you leave your LED lighting on in Vegetation

Discussion in 'Lighting' started by Headhunterpipes, May 15, 2018.

  1. There was a thread that was asking this question and for the life of me I cannot find the thread .

    The members who replied to the thread were not in all agreement on how long to leave the lights on.
    A fair amount of members are 24/7 others lean toward 20/4 or 18/6.

    I strongly advised 18/6 because of the books I had read but my books were published 10 or 20 years ago and LED is the new light on the market and therefor hasn't had decades of testing by the cannabis growers .

    Allot of members chimed in stating they have there LED lights on 24 hours a day.

    I have been doing some research, Books, a person who is a consultant for several large commercial grow warehouses and my horticulture college professor.

    This is what I learned, when the lights are on the plant intakes CO2.
    When the lights are off the plant expels CO2 .
    What was said to me was the plants need a certain amount of darkness to expel CO2.
    Some of you guys might research this info.

    It was suggested that LED lights are set to 20/4 or 18/6

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  2. I always leave my LED on 18/6. I personally see better growth with that schedule
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  3. Out of curiosity... what makes Christopher Teague a credible source as well as an expert on the subject? Seems like a pretty unsubstantiated article imo
  4. I have experimented with various light cycles throughout the times.

    I say 18/6 - 20/4 are good cycles. I am running 19.5/4.5 currently and think it is a sweet spot.

    Cannabis has been proven to NOT need a dark cycle/ but some evidence (and accounts from many growers) suggest the plant looses vigour after 1.5-2 months and hits a wall so to speak. I believe it has to do with the cells eventually lose efficiency due to light stress. Some evidence in regards to wheat; say that in outdoor fields: Wheat has maximum photosynthesis in the morning and evening; during mid-day when the sun is most intense the plants stop photosynthesis and enter a form of "protect mode" to keep cells from being damaged by high levels of radiation. (aka light)

    Blue light helps this function in the plants. (Notice plants have more vigour in blue light compared to red/yellow?)

    So I would suggest not running a 24 cycle for much longer than a few weeks, and then back the cycle down again for some darkness. Its also bad for a LED to never have a cooling period; unless it runs at or less than 100-110f. Get into 135-140f+ and your stressing your components in my personal opinion. COB LEDs manage heat better than 1,3,5,10 watt diodes; due to the way they transfer heat I believe. If you burn out a led or two; or a driver fails inside the light, just open the light up and fix the problem. They are easy to fix/modify if so desired.
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  5. I do 18/6. But I was reading on Mephisto genetics website on their grow guide. They say they run mostly 24/0 on autos. They don't have reduction in quality. Their plants are happy and it shaves a few days off the cycle time. These guys know more about growing bud than me lol, so I think i might switch to 24/0 after this summer. Wait till the price of energy goes down.

    This advise from them is for autos.

    Mephisto Genetics

    It's a pdf file. Was going to quote them but I couldn't figure out how to copy from a pdf. It's under "Light cycle for autos" on page 9.
  6. #7 CBDBurner, May 17, 2018
    Last edited by a moderator: May 17, 2018
    Seedling 20/4, veg 18/6, flower 12/12, right before chop 24 hrs darkness
  7. I've been doing a 6/2 light schedule since germination :hello:
  8. How’s that working out for you I’ve heard of that schedule
  9. Plant seems happy enough, its growing wherever it can.
  10. 6 hours of light and a 2 hour power nap ha ha.. OK so thats three 8 hour days with a 3 ta 1 ratio of light to dark schedule in a single day.. (18/6 but segmented into 3 complete cycles).. Soo.... Whats the benefit?.. Surely you cant trick the plant into thinking its Wednesday when its still just Monday night .. Right?? Lol I've gotta know more about this.. Somebody rant on it
  11. As in 6 hours on 2 hours off? Never heard of that before like.

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  12. Yep, 6 on, 2 off, 6 on, 2 off, etc. It's essentially an 18/6 with breaks more often. Try This Highly Recommended Cannabis Lighting Schedule

    There's not a whole lot of info on it but I figured I'd try and and see what happened. So far my plant is thriving with it. A few users on reddit have used it successfully too.
    • Like Like x 1
  13. Haha, that's funny but I don't believe its to try and trick the plant into thinking it's a new day already, though you could be right!
  14. Gave it a read and Its an intersting theory anyway. Ill stick to my 19/5 though lol

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  15. #16 killset, May 17, 2018
    Last edited: May 17, 2018
    24/0 cannabis being a c3 plant, it does not need nor benifit from a dark period in veg. My scrog nets fill faster on 24/0 resulting in a shorter veg period and quicker turn arounds. Scrog nets give a defined area to analyze growth.
  16. We are guessing ,, very few of use are using exactly the same LED lights .
    Some LED lights are more powerful then others, straight up not all LED lights are the same .
    Some LED light install more UV and IR bulbs then other and that will have to do with how close the light is and how long the light stays on ....
    You would think one 300 w LED light is like all 300W LED lights made in the world and that isn't even close to being the truth.
    I can make a custom Cree 280 W LED light using SolarCure bulbs that is lower Wattage and emit 10 times brighter light then the a Mars 300 w led light made in china.

    Once we consider that all these lights have different amounts of UV and IR bulbs at different frequency it changes everything.
    One light might emit to much UV or IR lighting that the plants will burn, another light might not have but one or two UV bulbs at a lower frequency and can be left on 24/7 without doing damage to your plant .

    I know this, mother nature has been growing plants allot longer then me and all plants on this planet have certain amounts of darkness.
    As far as I can tell we have all been trying to copy what mother nature has been doing for thousands of years.
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