How high?

[goldhead]

how high do the plants have to be before i could start to put the 12/12 cycle on them???

[Ivan]

They can be as high as you want em. It dont really matter but if you are growing outside I keep some of mine in pots and take the pots outside so then I can leave some to grow full time in the ground on there own and some I can bring in when I think its time.
Hope Ive been a little help