Got this from an electronic pub I have: "You should begin your flowering nutrient (high in P). Some growers believe that it is important to begin using flowering nutrients 1-2wks BEFORE switch over the light for flowering. Others begin flowering nutrients when they switch the light. There may be benefits to switching nutes early but it is certainly not a requirement." Anyone had any experiencing in switching nutes BEFORE 12/12 begins?
I use Open Sesame the week before, seems to work but I wouldn't doubt if it didn't. I've not done a true comparison with or without, but I'm getting good results from it. What I mean is that I haven't taken 2 clones from the same mother and tested it, but it seems to work. Would be an interesting thread if someone decides to test this.
I've heard that it can speed up the transition phase. But really, it's not much of an issue, your grow formula will have enough PK for the first week or two. Once they start packing on like crazy is when you need the higher levels. Oh, and if you're in soil, it can be good to give them a heavy nitrogen load right on the flip. Holds them through the stretch and into mid flower, and will have burnt out come flush time.