Hibiscus plants are divided into two main categories, the tropical flowering hibiscus and the hardy flowering hibiscus family. The tropical hibiscus is not winter hardy in areas outside of climates such as the state of Florida. The Hardy Hibiscus is reliably hardy in zone 4 and, with extra protection, marginally hardy in zone 3. Hardy hibiscus can be grown and enjoyed as far north as Minnesota and New York.
Hardy hibiscus need very little care over the winter; they are root hardy to about zone 5 with no protection. They die back to the ground each year. Hardy hibiscus grow very quickly once they break ground in late spring.
The tropical hibiscus will not tolerate more than a night or two of light frost. One hard frost, below 25 degrees could kill the plant. These plants are native to sunny, warm and usually humid tropical places. They would need to be brought inside in zones outside of zone 9 before temperatures drop below 45 degrees Fahrenheit at night to avoid damage.