You definitely can, but it's easier to run into over feeding, rootbound issues, and problems in general. Not to mention the yield isn't a whole lot. It's amazing what going to a #1 size container from a solo cup does. When I did SoG, I would transplant from solo cup to 1 gallon, veg for a week more until the plants were 8 - 10 inches tall, then put them into flower. Harvesting 5-10 every couple of weeks usually getting around 6-8 OZ's a month. lolYou can grow quality weed in a Solo cup, just not a bunch of it. Personally, I think solo cup grows are killer. There is a user on RIU that was the winner of High Times Top Hot Pot Shot of the Week using beer cans and CFL's. He pulls 4 oz's a month doing a SOG style grow. His grow pretty much shoots down the idea you can't grow quality weed in a small container.