Mexican Evening primrose (Oenothera berlandieri) is a wild flower used as a spring and summer bloomer in very hot climates. It is used as a groundcover or rock garden plant and can become invasive but this easy to grow perennial can be a challenge to grow in a pot. It does not like potting soil with organic matter nor does it like fertilizer. It prefers lean, sand soil that drains quickly. Use a cactus potting soil mix and don't fertilize and perhaps you'll convince this wild thing to contain itself. Keep growing, Marianne Binetti