friendowl is correct. They make a net pot for just that reason. If you can't fine one of those you can use a one gallon bucket and drill a bunch of holes in it. You would need to have a PVC pipe or net pot to give it strength but that would give you a bunch of room to grow. When people grow KBS (trees) they have one 5 gallon bucket per plant and use lava rock so the plant has a good strong root system.

Just another idea to think about.