Along similar lines, my indoor hyacinths flowered in early January and
I wasn't very pleased with them. The flowers weren't what you would
call spectacular and they were dwarfed by the leaves, which were
easily double the height of the flower. Is this normal? I'm guessing
that the NPK of the compost is to blame.

I watered them, gave them a bit of feed once they started flowering
and they got a lot of light too...

TIA
Nick