slowly up the P until you reach your "Bloom" formula. The plant still need N and such even after it quits growing stems and leaves.
Use my nute calculator! lol, it should work now for liquid nutrients, i swear... 96% certain it works!
100% works for the dry stuff.
Anyway, you can ensure you provide enough of everythign and boost the P if you want by varying the dosage of all products used and instantly calculating results added up for your viewing pleasure.