I grew a couple of the Indian Tribe series, reputed to be the hardiest... I think Zuni and Hopi, for a few years in northern Iowa 4a, but they turned up their toes finally. I never mulched them or anything. They'll die back to the ground, but as they bloom on new wood, you can get a 2-3 foot tall bloomer... not probably worth it for most. If you have less hardy types, no chance.

I fell in love with them on a visit to Georgia last year. I've been crepe myrtle obsessed ever since and even wrote someone at ISU about global warming vs the new USDA chart hoping I'll soon be a zone 6 :)
I was astounded to find them here in Iowa.

Haven't tried them. From what I've read they probably would not make it anywhere in Iowa without some protection. You should try a hardier form of Southern Magnolia. I have two that survived in the ground last year by mulching alone. They are now thriving and I hope they will bloom next year. I also bought a Brackens Brown Beauty Southern Magnolia that has bloomed this year already. If you still want to try the Crepe you should read a book written by Dr. David Francko entitled "Palms Won't Grow Here and Other Myths". The book doesn't just cover palms, it covers a wide variety of trees and other palnts that can be grown far north of where people think. He talks about Crepes as well.

I actually have a zone 5 magnolia tree that I've purchased for an accent tree. I grew up in Southern Cali and had one in my front yard growing up. I doubt this will be anything like the California one but it stil will remind me of my child hood home :~)