from what I understand, it takes time for the plant to mature before it starts flowering (from seed) hence the vegetative state, but if its a clone it may begin to flower because the clone is from a mother plant, which may be mature enough to flower if you induce flowering by putting them on a 12/12 cycle or outside. outdoor is totally different in that aspect, seasons, weather, time etc are all a factor. the 18/6, 12/12, and 24hr cycles are mostly for indoor use because it's a controlled environment, if your growing outdoor it's gonna take a lot longer to produce bud but you don't have to worry about the 18hrs of veg, just make sure your planting your seedlings at the right time of year for outdoors..