I'd remove it from the container and plant it in the ground. The container may be unnecessarily restricting root development, depending on size. The container is also compromising good drainage by being sunk in the ground. Potting soil tends to be quite moisture retentive and the garden soil surrounding the pot is hampering the movement of water freely through the drainage holes.

Thank you. The hard part is getting to it. It is planted next to an old rose, and behind lilies that are pretty tall by now. I will do my best to get it out of the pot and into the ground.