I'm at a loss with your zone being warmer than mine; you must have endless possibilities. This is a situation where you are best off asking at your local nursery. But if I had to come up with something... begonias?

What about some of the scented geraniums. They come in lots of "flavors" - peppermint, rose, balsam, etc. Or, pots of herbs, like mint (keep in pot, or it will take over). Mints come in a variety of flavors, from orange to chocolate. And you can stick a leaf in your tea in the summer!

New Guinea impatiens would give you some color. I am assuming you are talking about plants for your porch?

Susan