Leaves are turning yellow. Planted approx one month ago. What's going wrong?

Well, I'm no florist, or botanist, but my grandmother did teach me this much. Sunlight and water. I mean it isn't that hard. Gardinias are a plant I've never heard of but the fact that you sent a flower to your great-grandmother for Mother's Day shows great love. And that's another thing my grandmother taught me. A little TLC goes a long way. You posted something like "it is on my pool deck getting a minimum of sunlight". That's not good. More sunlight and the chlorine in the air around the pool MIGHT just have something to do with it. Like I said, I'm no botanist or florist, though. Tru a better-lit area, and one not so cold. I'm assuming your pool deck is outside, so bring it in out of the elements. Bring it into your house. Water it until the topsoil turns moist. That tells that the whole pot is evenly wattered. Don't drown it though. You want moist, not wet or soggy. Also, I've heard that it doesn't hurt to talk to your plants either. I know it sounds crazy, but if it is, then there are a lot of crazy people on this earth, because I've heard of a lot of people doing it. Best of luck to you and your great-grandmother.

~Zero