Every year more often than not I spot Delphinium at the local nurseries in early spring. Delphinium I consider to be the monarch of all perennials, and if I lived in, say, Virginia or Massachusetts, I would have an old (or old-looking) stone wall and plant mostly Delphinium. In the deep south, Delphinium can be a joy, so long as perspective is kept and expectations modest.
Delphinium does not like hot, humid conditions, and as the sun begins to beat down upon us, the Delphinium will fade (not prettily) away. However, if we grow it here as an annual and enjoy the brief glory before the inevitable fall, then it is hard to find a more spectacular flowering perennial.