Closet grows with little ventilation can be done; I'm doing it now myself with a plant I couldn't bear to kill...but it's a beotch, so I spent some moolah on a grow tent and a real light and fan and stuff, because dealing with this closet is irritating me no end. I've got around 520 watts (real watts) of CFLs in a tiny-ass closet, using a $20 box fan for cooling, with the door a third open. It's working. I could probably get it all the way through flowering this way, but it's just too much of a pain in the ass, and it's pissing me off. Mainly, the plant in there is getting too big for the closet (it's 46" tall now, counting the pot), after a week in flowering (so it's going to grow quite a bit more).