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    Andrew H
    Mar 25, 2021

    Switching from 18/6 to 20/4 or even 21/3 mid-Veg

    in Grow Community

    Currently in my veg tent I have a few gelato seedlings (1-3 weeks) and an older Sundae Driver (~9 weeks) that have been under 2x 150 W LED grow lights on 18/6 light cycle for the last 9 weeks. I was thinking of switching to a 20/4 or even a 21/3 light cycle to speed up the process. Is there any reason why I shouldn't do this?

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    SinnerSpread
    Mar 25, 2021

    Nope.

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    Andrew H
    Mar 25, 2021
    Replying to

    So why is 18/6 cycle so prevalent? I'd argue that the best metric for determining a grows success would be grams/kWh. Is there any data to suggest that an 18/6 light cycle yields a higher g/kWh than 20/4? i.e. do you get diminishing returns in terms of growth once you push beyond 18 hours?

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    Mr. Grow It
    Mar 29, 2021
    Replying to

    @Andrew Harper This is a controversial topic. But basically, there are plant processes that happen during lights off that are important - i.e. secondary metabolites. I've ran 18/6, 20/4, 24/0 and didn't see much difference in growth. I did see an increase in my electricity bill though which of course is no bueno.