Are there any signs of male or female plants that are shown before flowering?

I'd like to know if plants show characteristics of sex shown before flowering actually begins. Are there any differences in plant shape or development? Plz help

Some say males are taller and lanky, females more compact and dense - but that's not really any indication because those factors are directly correlated to growing conditions and genetics.

Your best bet is to wait for pre-flowers, or take a clone and 12/12 it.