there is no "average" Tiny. for flowering i put 4 clones in a 12" x 12" space, friends of mine put one clone [veged longer] in the same space.other growers can LST one plant and make it cover 10 square feet or more. in short a plants "need" for space is determined by the grower not the plant.I'm refering to indoors of course, outdoors is a whole different ball game i'm not qualified to comment on as my experience is so many years past .