Answer: The site you describe and the way you prepared the soil should give your gardenias more than just a fighting chance. If you purchased one of the hardy gardenias, such as 'Kleim's Hardy', you should have success wintering them over in your garden. Kleim's Hardy is rated winter hardy to zone 7, which happens to be your gardening zone. This gardenia is hardy to about Zero degrees F. It sounds as though the site is protected from wind, which is great for winter protection. The good news is that even if Kleim's Hardy should experience partial dieback in a really cold winter, it almost always regenerates from the base.
Hope you purchased hardy gardenias!
Q&A Library Searching Tips