Seems like the guy in hydro store needs to find a..... more suitable job!
Even my girlfriend ( who doesnt know the difference between P and K element!) knows autos are time bombs.day lenght variation(20-6 or 24-6 instead of 18-6) is the only way to flower later and yet not suggestable as stress effect is more than increase in growth.
And PK shock is the only way to prolonge flowering stage that im aware of.
Good luck
I don't get the 20/6 24/6 none make up a 24h light schedule?
Autos don't flower due to light periods, they flower by genetics.
Some early than others but around 4 weeks no matter how much light you give her. 24/0 20/4 18/6. The amount of light will influence her size and yield but not when she flowers.
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