2.5-4 gallon potters at the most I would say for autos, as for comparing two plants in two different size potters for autos isnt an accurate comparison. You could have two of the same strain, in the same size potter, from the same seed pack, and they be very different in size and structure. Autos are funny like that. Same with regulars, but the size difference usually isnt as drastic. Autos are easy to grow, will you get the same results taking care of them properly rather than half ass? No you sure as hell will not. In my opinion regular plants are, I think the term was piss easy to grow. Anyone could grow them as well. Put the bitch out side and water it, I guarantee it will grow, no matter what strain it is. But if you take care of something properly it comes out much better. So do I think an auto that has a potency close to where the parent plant is, is easy to grow, no its not. Is it easy to grow one and it live and give you some half way decent bud, sure, anyone could do that. Especially indoors.