Hi Yo - I use 1 gallon pots to get approx 18-24" plants, and 1.7 gallon pots for 24-32" plants, 4 in a 16"x16" space with 24" vertical grow space until it gets too hot under a 150W HPS. If a taller plant is bushy, I have to take 1 or 2 out. I average 2 to 2.5 oz total under the HPS or about the same wattage of CFL bulbs. Not a big yield, but I grow more than I can smoke, so it doesn't matter. The plants do get bigger in the bigger pots, but don't seem to yield significantly more. It may be because I have to heavily train the taller plants, making for a dense canopy, and the bulbs have limited penetration. My experience, hope it helps.