Trish, Gardenia are not an easy plant to grow they need a green house although you can sink the pots in a plunge bed during the warm summer months.
It will need a 6-8 inch pot with John Innes number 2 potting compost, that will have loam sand and grit in it.
it needs to be kept above 12 degrees C and below 18 degrees C and water well, on hot sunny days shade slightly and make sure there is air movement in the green house, stand a bucket of water next to the plant for humidity or damp down the greenhouse paves.
As I said not easy although with over a hundred different species there will be one to buck the trend, some body may come up with a simple remedy, I will look forward to that and learn.
Frank
