We have recommended many plants for attracting butterflies and have even planted a butterfly and hummingbird garden in our water garden display area at Valley View Farms. Our signs have butterfly icons on them if they do attract butterflies as either nectar producing plants or as larval hosts. Some butterflies are plant specific, like the Monarch that is attracted to Butterfly weed (Asclepias tuberosa). Swallowtails and other butterflies are attracted to a wide range of perennials and shrubs. Annual flowers like lantana, and herbs, like dill, also draw all sorts of butterflies.
We have a very informative handout available at the store that highlights plants that are attractive to butterflies and hummingbirds. I am personally in awe of the attractiveness of the Clethra. I'm sure our wet spring and summer have a lot to do with how large and healthy this particular plant is right now in my garden.
Butterflies are a bonus to our summer gardens. Treat them well by avoiding pesticide use near them. Keep some of the garden a little wild as well groomed gardens are not a favorite habitat of many forms of wildlife.Water should be available to butterflies as well. Most importantly, enjoy butterflies and your garden this summer