It is apparent from the photo you posted that it is not a China Doll. Glad you got clarification on that.
Gardenias need to be quite potbound, cool temps, soil kept moist, protection from direct sunlight and their roots left undisturbed. It is hard to advise you on the watering because we don't have details on the repotting.
Gardenias are not easy plants and they are quite demanding in having all of their requirements met and not very forgiving when they are not.
