I know I have 4 autos in a 3x3 in five gallon pots and is pretty crowed to water. Next time only doing 3. So I would say depends on pot size can’t see doing in less than five gln if soil so 3x3 would say three.4x4 4 5x5 5 and so on is how I will plan for here on out. Having the blumatt system...