Don't believe the auto haters. Some have pointed out YES you can run a photo 12/12 from seed, and YES SOMETIMES it will finish in under the 90 day mark. HOWEVER this isn't true a good portion of the time. For instance I have a 100% sativa going (though its a hybrid, its a very sativa pheno with no indica traces breeder claims 75% original haze and 25 % northern lights). It is now entering it's fifth month, under 12/12 since week two or so. It looks like it still has another 3-5 weeks left in it as well...
Meantime I have grown out THREE sets of autos. Yes THREE. under the same lights. I started with 60 day lemon about 3 weeks before the long tooth strain. iti finished 35 days into the life of the haze mix. At the same I planted the haze mix, planted another 60 day lemon. This was cut over a month ago now. During that time I also planted auto moscow, and auto blue. 2 months into the life cycle of the haze. That has been done for two and a half weeks now.
I bred the lemon and moscow and blue, and have my own breed of seeds going now, it is week 3 and they have pistils all over them -- looking to be done in around 5 weeks perhaps? Which is what I could TRY to say the haze will be done in, but that is my HOPEFUL guess.
So, growing this 20 week very hazy strain by itself the past five months, I'd have zero bud. (I have 3 of them goin) meanwhile I've harvested 7 autos, three seperate occasions, months apart during the same time. I got around 7 oz from the autos all together.
Point is, the flavor and potency of the autos was EVERY BIT AS GOOD as any photos I've smoked or grown, or seen a partner grow. PLUS making auto seeds from a plant or two ensures you can plant a few WITH any grow, no extra fee, and get extra bud to tide you over till the "most potent strain that takes 20 weeks" you want is done.
12/12 from seed does nothing if the plant has a 12-20 week flower period. 7-9 weeks for an auto means 2-nearly 3 complete harvests depending.