If you google the Xerxes society, they have a whole list of plants for varying climates to create some fantastic butterfly gardens. Plus they are a non-profit org. Anyhow, I got a few of their pamphlets for my mom and sisters so we could make butterfly gardens together. Oh, and plant MILKWEED - there are several species in North America and the plants are essential for the monarch butterfly. Plus they attract these really beautiful blue-purple iridescent beetles!
