Although I do not have any particular recommendation but if you tell us your zone, approx location, state, etc it will make it easier for others who know this stuff. I am assuming you want to grow outdoors all year round. I believe there are some zone 8 gardenias but have no personal experience. I have grown regular gardenias before. It got stolen. Now have a dwarf gardenia for the last 8-10 years.

Various gardenia cultivars continue to be presented to the retail market as outdoor plants here in my cool summer part of USDA 8 but I rarely encounter established plantings of them that look very successful. Also with plants of this nature there is always the question of what they are going to do when the next sharp winter comes along. With them looking good up to that point having no bearing on what happens when the thermometer falls down to what is simply too low for the particular kind of plant, regardless of other involved circumstances.