I love gardenias but you can't overwinter them here in NJ. But there is an evergreen azalea called Hardy Gardenia that looks a lot like a gardenia. It is a small and pretty shrub. No great gardenia smell, though.
Too bad...the smell is what it is all about!!! I have two potted gardenia bushes in my patio right by the sliding door. The fragrance is wonderful in the summer when the door is open!!
I live in Pa, and I remember my mother having a "house plant" Gardenia. She had it in a basket plant stand it kinda looked like a small bush. Over the summer she kept it on her porch in the shade and brought it in the house over winter.When it bloomed the fragance went through the whole house. Maybe you could try this, if you can find a small one.
I did do this years ago but either the gardenia or I gave up. I over winter some things but I wonder why sometimes. (OK, I really know, i can't just let them die.) In the spring my poor plants look pathetic while fresh half hardy perennials or annuals in the garden centers look great : )