Originally Posted by Gabe15

Bananas can be held in small containers for a long time with no real ill effects if managed well (not over fertilizing is important and easy to do with soluble inorganic fertilizer). They will just stay small if kept in a small pot. The question really is what do you want out of them? If you want them to attempt to fruit one day, they will need much larger pots. If you just want some interesting looking plants for foliage, you can keep them whatever size you want by keeping them in smaller pots.