i think im gonna start at 1 gal transplant to 5 then transplant to 10 i read in hightimes that if you fold a 10gal grow bag to make it shallower it results in shorter bushier plants w. greater yeildsyou can get them at any good hydro store if your talking about the poly grow bags. they are real cheap and work well for one grow. i buy them just to start plants.