It very much depends on what kind of Hibiscus you have, but yes in general freezing will kill most of them. If you have picture upload them here and we can advise you better. HTH CHris
Hi Walker, As Chris stated, if it's a tropical hibiscus it won't take a freeze. Here's how to tell if yours is a hardy or tropical hibiscus. http://www.trop-hibiscus.com/gindr.html Newt