Answer: Based on your zip code, you are gardening in zone 5A or the coldest part of zone 5. Depending on your garden's microclimate it might actually be as cold as zone 4. I would suggest you work with your local professional nursery staff to identify azaleas that might do well for you. They will have localized experience which is much more accurate than going by a reference book. The University of Illinois does indicate that this one is hardy to zone 5A, which is encouraging. It also notes it is semi-evergreen there so I would expect it to lose foliage where you are no matter which zone specifically you come under, this is not so unusual for azaleas at the colder end of their range. I did find several commercial nursery sites also listing this variety as hardy to zone 4. (Note that there are several azaleas named Karen, one from Girard which is typically listed as zone 5, and another Kurume which is even less winter hardy.) You may need to cut and paste the complete url into your browser to make it work correctly.
You may also be interested in some of the hardier, smaller evergreen rhododendrons as described toward the end of the following publication, several are listed to zone 4.
I hope this helps.
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