Sup man,
Purple stems are a good sign of cooler temps. Is your box cold cause yours are so purple is wierd? id ask in the plant infirmary fourm?
Dont give her any more veg nutes if shes going to be flowerd soon.
Use the Blooming stuff an go easy if you over do it shes toast. start with 1/4 strength an work it up slowley once a week tell you flush be for harvest.
I would make your bulbs mainly red spectrum for flowering also.Keep them cfl close an it wont stretch much, just tight nodes an more veg time
I use fim/topping to slow the vertical growth an bush em out alot more. I would top em soon judging by the size of your box.
P.S. Also grind down your plug in adaptors in your power strip so they install flush. Then epoxy em in place the look like they are going to fall out an burn your baby lol.
But its looking good.
Good luck grower!