Hi there, it died. I have no idea why.
I got a new one - a Tahitian Gardenia that I put in full sun (6 hours) on my porch. Online instructions stated full sun is okay for Tahitian Gardenia. One of the leaves has browned a few days ago, but it has stopped. I'm hoping this Tahitian Gardenia will be everything I want and more.
Thanks for your suggestions. I'll look into those fertilizers.
Here's two pics of my Gardenias:
