Similar and different...
I, also, had some languishing in pots in that sometime-excuse-of-a-thing called the 'nursery bed'.
There, too, they rooted vigorously through the bottom of the pot(s). I could not leave them there as they were obstructing an intended view. When it came time to move them, I didn't get much root, despite my best efforts with pick-axe digging round them - the roots were delving deep. But, having got them out, I pruned the roots back to undamaged parts and then pruned the tops heavily (over half), and removed more leaves back to the petioles (I like to let them reject the petioles in their own time, allowing them to abciss nicely). They then got planted out in the usual local soil (deep marl with some stones), staked, and watered. I presume they all rooted well, because they soon began pushing out new leaves and shoots, and they have flowered very well this spring. They are four years old.
Sequential piccies attached...
BTW: they are Bauhinia variegata.