Ask-a-Dave's-Gardener: Gardenia Help, 3 by lovegardenia

lovegardenia wrote:
I love gardenias. I have attempted to grow various store bought gardenias over the years and they have all died no matter what I tried.

At the beginning of this year, I bought this beautiful gardenia plant from Lowes. It was doing extremely well. It had flowers blooming throughout the year and grew in size. I even bought a bigger pot and repotted the plant. Then within the last week it started to wilt. Some of the leaves are beginning to turn yellow. I would really like to try to save this plant.

Anyone have any ideas as to what is wrong? I did not change how much water it was getting. I live in Southern California and it is starting to get colder at night. Is that an issue? I have attached some pictures if it helps.