how cold hardy can hibiscus be? do they have them in zone 3?

Answer 1

Yes, there is such a thing as a "Hardy Hibiscus plant". Most are tropical but 3 plant breeding brothers named "Fleming" bred and created a line of very hardy, hybrid plants. They called them the "Moscheutos" variety. They are cold hardy all the way down to -30 degrees! They grow in zone 3 and reach a height of about 30" and grow best in full sun. There are a few different color combinations that come with the "hardy" hibiscus. "Crown Jewel" is a nice one. It is a white flower ruffled with red streaks that radiate from the center eye. Another nice one is "Fantasia". Here is a link with some pics and info on the Fleming Bros. hardy hibiscus. Hope this answers your question.
http://www.flemingsflowerfields.com/flowers.htm
http://www.soonerplantfarm.com/index.cfm/fuseaction/specials.specDetail/recID/30/index.htm

**Billy Ray**

Answer 2

Well, there are the tropical Hibiscus that aren't hardy except in like zones 9 & 10. There are the hardy hibiscus that are hardy zones 5 - 9. However, according to this artical they can survive zone 4 and with special care it is possible to help them survive zone 3.
http://www.bachmans.com/tipsheets/Perennials/HardyHibiscus.cfm

I live in zone 7 so I don't have to do anything to my hardy hibiscus. However, I have some idea of what you may have to do to protect yours. Since hardy hibiscus is a woody perennial, they will die back to the ground for the winter. You will need to mulch over you hibiscus heavily to keep it protected from your freezes. Regular mulch will do, but straw is a great way to mulch for the winter. Anyhow, I hope this helps. Believe me that the hardy hibiscus are worth all the work. Although the blooms only last one day, they are in constant bloom and the dinner plate sized flowers are stunning.
Good Luck