donpaul.p;1875699 said:stretch time can vary depending on how mature the plant is, if the plant is fully mature during veg then it can flower within a week of flipping 12-12, mature plants show sex even under a veg schedule
when i use 18-6 or 17-7 for veg my plants usually show sex around week 6 onwards and no more than week 8,
when i grew under 24-0 it took much longer and most did not show sex at all until i flipped 12-12.
you also get more stretch when going from 24-0 to 12-12 then you do going from 18-6 to 12-12.
the reason plants stretch when you flip 12-12 is because the plant is trying to find the light again, then once its started flowering or got used to the light schedule which is around day 21 of 12-12 then it stops stretching,
plants do at least 3 things during the lights out period, they repair damage done during the lights on period, the send nutrients and energy back down to the roots and this helps with root development which is why 18-6 was proven to produce the best root growth during veg, the other process they do during night time is stretch, their doing this to try and find the light, just like the lower branches do if their not getting light or if you have a plant thats shaded then it will start to stretch so it finds the light again.
things that i know from my own experience that stunt the stretch phase is over watering, when i first started growing i over watered and my plants just wouldnt grow and did very little growing during the stretch phase