ADHD2THCanswered grow question 4 years ago Yes, what if? All jokes aside, there are a million answers to this question. Assuming you are talking about a fem photoperiod, you'd likely move from veg to flowering relatively quickly, and isn't typically recommended for beginners from what I understand. If you are talking about a fem auto, 12 hours isn't really enough to give it the full dose of light it needs to produce quality bud. Can you you do it? Sure! Should you do it? Not likely.