i tried the extended dark period before the 12/12 switch and cant say it made any difference so i wont bother with it again. as for nutes, personally, i continue giving my plants grow nutes(the stuff for the vegging) all the way thru my flower cycle but at a gradually reducing level; dropping from 5ml per litre of water to 4 to 3 and so on but i keep it at 2ml per litre to the 2nd last week, it helps keep ur leafs nice and green, as for the flowering(bloom) nutes i strat with 2ml per litre and increase 1ml per litre each week until a max of 5ml per litre and then reduce it 1ml per litre per week. i dont feed any nutes on my last week, i just give them water, this helps flush an shit out of the plant creating ,imo, a cleaner, less harsh and sweeter smoke. at day 11 and day 35 of flowering i add 1gm of epsom salts( per litre of water) to my normal feed/water mix. epsom salts are magnesium sulphate, this helps with nute lock issues i.e the plant sumtimes doesnt take all its nutrients and misses some vital ones, u can get more detalied info on epsom salts on the net just google it. this is for a soil grow btw.