Hibiscus blooms - how long do they last?

I've got a lovely hibiscus on a window ledge, west facing... It is flowering prolifically, but they only last for a day or two at most before curling up. Is this normal? Otherwise, it looks healthy - lush dark green foliage, no leaf curl / discolouration etc.

 

Perfectly normal - the flowers of the hibiscus do not last long - just remove them to keep the plant looking nice.