um i would highly recommend keeping them outside it will probably finish by October and also he means hps/metal hallide bulb which you would need a reflector, ballast, and bulb for which is kinda pricey but worth it. and yes you would need to make sure your plants get no light whatsoever during the night so you would need something like panda film or Mylar. also you would need to buy a timer because its hard to turn the light on and off by hand the you would need some sort of fan or ventilation to keep it cool in the closet and after all this you'll still get less then if you just leave them outside. but are you doing a guerrilla grow because if so i would bring one in personally i have had every plant i have put out side stolen besides in my own yard. but dont let that scare you guerrila grows are fine i just got unlucky. but dont get me wrong indoors is fine but if you dont have the right equiptment or the money to get some of these things your better off leaving them outside.