From my experience, there is no such thing as root bound. As long as you give the plants what they need, they will be fine. When you're growing in party cups, the plants need allot of care and love, since there is only 16 oz's of medium, the plants demand more then a plant in a regular pot, since a regular pot has more soil which has nutrients in it. Do you got a journal going or anything? reply on my page cause it wont update me if you reply here