Is Hibiscus rosa-sinensis hardy?

Is this hibiscus hardy in zone 9, or do I need to protect it from frosts?
Thank you for answers

They are hardy in zone 9, but it's definitely not a bad idea to protect them if you are expecting frost. A little frost shouldn't kill them, but I've found that it can cause them to lose their leaves and be rather slow to get going again in the spring. If I keep them in my greenhouse then they stay green and often blooming all year long.

I am in Zone 9B and had some cold snaps in the winters of 2009 and 2010. It killed 4 of my Tropical Hibs. As ecrane mentioned, rest of them lost their leaves and did not grow or flower properly the next year. I don't have a greenhouse and they were planted in the ground, so the cold dealt a bad hand.

Thank you. I really want to put them in the ground, getting to big to keep in pots. I'll p0lant next to house and protect-should work?

If you can protect it from northern exposure, keeping them near the walls should work, at least worked for me and I was able to save a couple of them.

Good luck.