Thanks for the reply! The pots are 3 gallon and it's been about a month since they were transplanted to them. Yesterday I cut some additional drain holes at the bottom of the pots and discovered a few roots.

Think they may be rootbound too? I don't have any 5 gallon pots, but I have several 3 Gals. Would cutting the bottom out of the pots and stacking them on top of half filled 3 gal pots work?