We have a couple of gardenias in 12-inch pots in the patio.
They can tolerate high temperatures as long as they are not directly under the scorching afternoon sun.
They can also stand our dry, cold winters that can drop to 35F.
One thing to note, these are mealybug and white fly magnets. Make sure you check the plant frequently for any signs of infestation.
However, since these are non-edible plants, you could use a systemic pesticide to prevent any bugs from taking hold in the first place.