Darkness in a tent/room is much different than a cloudy day for sure. The sun still has certain rays that penetrate through cloud cover. Also if something obstructs the view of the sun to the plant there is still reflected light from all around. Being in a dark tent/room for a day is much worse than being outside on a cloudy day...


Your plants will be fine. Added darkness changes the hormone levels in the plants... Takes time to do so. As long as you dont keep messing with the light schedules you will be good.

Some people actually give their plants extra dark hours when they switch to 12/12 to promote hormone buildup to start the flowering process early. Why not just change to 12/12 now?