The, unfortunatly, hib flowers only last 1-2 days..There's nothing we can do to make them last longer.
Do you know if your hibs are tropical types? If so, the good thing about tropicals is that they bloom yr round wheras hardy types for lower zones go dormant in winter. All stems die back unlike the tropicals..
It's sad hibs work this way, but that's just how it is. Toni

The, Hibiscus flowers last a day, maybe two if you're lucky. Give the plants time to adjust and it'll look good, but as far as flowers, they're short lived..the thing about hibs is if given good care they'll bloom throughout the yr..They don't go dormant like some flowering plants. Toni