Auto flower lighting issues

I was shipped Auto Flower seeds accidentally. I originally ordered Fem.
My question is they started to flower while under 18 hours of light, can I leave them at 18 hours for the duration of the grow to get bigger buds or do I have to go back to 12 hours of light?


18 hours works for 95% of autos… some stubborn ones need a lil hell to get started… or finish for that matter… 18 hours allows you to use dli method to achieve a certain amount of light over x amount of hours… in theory you can run a lower ppf over longer time to get same dli as more ppf in a 12 hour period for same dli


What is “dli”?

Daily light integral… a certain molar mass is recomended per day…m which is
seconds in a day
Ppf per second x
Period you want to run light for
Will tell you how strong your average light cover needs to be to achieve desired molar mass a day… autos can run weaker light for 6 extra hours at 18 6 so you can run a 50% weaker coverage for 50% longer time … get what I’m saying…
There is a high and low acceptable dli value for all plsnts… outdoors the sun reaches 60+ dli in some spots of the globe
But plants on forest floors under dense canopy under heavily filtered light might be 10 dli or less… it will still grow a plant but not optimally…

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Welcome to the community ! You can stay on 18 / 6 light schedule start to finish or you can cut back to 12/12 if you choose to save a little on the power bill. Autos will grow under just about any reasonable light schedule. Good luck

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Welcome Porky!

IDK about all of the “high tech” details about lighting, but I usually run auto at 20/4 or 18/6. Have seen negligible effect on the plants.

They key variable on lighting is during veg & flowering phases. For my first four grows, I used what is called “blurpie:” lights on this forum by most. Despite all of my best efforts to kill my plants (I can explain what I meant there) my plants and resulting yields gradually improved. When I upgraded my lights about a month ago, my plants & yields EXPLODED. In other words a dramatic increase in size, density & weight of the buds.

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