well i have 2 plants that r 2ft(day 43 of flowering), and after 6wks of veg....but i have them in a 6" in diameter pot(like u said bout 1/2 gal) which i dont believe is no where enough.....my plants would have grown bigger but the pots r 2 small and the roots are all bound at the bottom of the pot, stopping its growth...so u could jus keep them in that 1/2 gal pot if ud like but id say atleast a gal....check my grow log(a few threads down) and u can get an idea of how they will look.....what kind of lights r u usin? im only usin 2 40w floro's...good luck brah...