I learnt a few years ago that to get great blooms from a Bird of Paradise
(Strelitzia reginae) the method is contrary to the norm...of repotting.

The secret...

If you have one of these magnificant plants, ensure that its roots are constricted... root-bound... pot-bound.

When I bought it, I repotted the plant into a 10" pot (on feet) and awaited the results.

It grew and the roots pushed the plant out of the glazed pot in which it was positioned. So I wrapped the roots in aluminium and bolted the sides together. See the pic...

After a few years the roots broke free of the glazed pot, cracking it!

So, for extra love for the plant, I 'repotted' it again, with its aluminium collar, into a reinforced concrete pot.

I'm happy to report that the resulting constriction produced an amazing 12 blooms.

without collar
with collar
And read about the NPK story. It'll inspire you toward great gardening excellence.