Eek! Considering it has been suffering so much it is a miracle your Bird of Paradise is still in such good condition. However, the fact that it has survived relatively unscathed should give you a fair indication of how it should be treated. The short answer to your question is yes. Strelitzias do not mind being pot-bound, as you have so graphically demonstrated! Nor do they like particularly rich soil. I would use ordinary garden dirt unless it is very impoverished and just add a little organic fertilizer + some wood ash, for those super flowers. You don't say where you live but I would also put this plant out of doors from as long as you can without exposing it to low temps (below 10C,50F). Good luck!

I inherited a strelizia reginae when my mother-in law passed away. Looked a lot like yours. I ignored the plant as much a possible, sitting outside on NE> corner of house, watered when it rained. Took in the laundry room before it froze, put it out when chance of frost was over.Last year I built a greenhouse,another story, and was firmly reminded by the dw to take it in. I sat and looked at, Grabbed it up out of its pot and stuck it in a larger one( on potting soil to raise it to proper height, took a stick and packed soil around it tightly. watered it-couple weeks noticed new growth, gave it a small handfull of 888 garden fertilizer,new growth accelerated. Few weeks noticed a funny looking new sprout, Double bloom. Saw why people grow these things. after blooms died, fertilized again (same dose)and have noticed 2 new bloom stalks , along with continued leaf growth. I water it about every three days, 14" pot. just my first experience, good luck, Jim