why 12/12?

[BobBong]

the days get shorter in the fall and force the plant to flower. eventually the days will reach 12/12 or less.....at least in the USA.

what he said

it makes the plant think that the days are getting shorter, by giving it more hours of dark.

to induce flowering it's suggested to have at least 12 hours of dark period, some people have been known to go 13 or 14 hours, different methods often result in different results.