My agastache is still in the pot, and it's dying there! Agastache is a plant for arid regions, and the eastern U.S. isn't in that category, especially not this year!

Have you every tried to grow Salvia guaranitica? Many butterflies as well as hummingbirds love it, and the electric blue color is beautiful. Lantana? Butterfly bush? Milkweed?
There are many choices!

Sherry

As Sherry said there are many choices. My preference is for pentas, especially the red ones. They will put up with a lot of wet weather and they bloom from spring to fall without needing much care. The hummingbirds like them also.

How about ironweed,buttonbush, or eryngium?

If it's wet there, try Swamp Milkweed or Clethra, and maybe some White Turtlehead.

Thank you for the suggestions. It's just a small spot, maybe 2' x 2'. Just big enough for one perennial. I was out walking by a local pond today, and the swamp milkweed was in full bloom. It was just beautiful, and the black swallowtails and tiger swallowtails thought so too, so that made my mind up. Alas, not a single Monarch or Monarch egg to be found. But the plant is still well worth growing as a nectar plant.

I also took a few small cuttings of a mountain mint that was growing there. The butterflies go crazy for that. I hope they will root so I can start some new plants. I will probably also go back to grab some seed in the fall.

So far I don't really have a butterfly garden per se, I am hoping to establish one for next year. I bought seeds for winter sowing of Joe Pyeweed, Liatris, pearly everlasting, and several other perennials, and I ordered a bottlebrush buckeye. I will be putting in some spicebush as well. Hopefully next year will be better!