A few of the colorful plants which attract butterflies include butterfly weed, coleus, butterfly blue pincushion, yarrow, sage, aster, coneflower, iris, coreopsis, phlox, goldenrod, heliotrope, alyssum and zinnia. Also fennel, Mona lavender, black and blue salvia guarantica and fan flower.
Butterflies also like butterfly bushes, sunflowers, potentilla bushes and bluebird shrubs. They also like vines which include Persian carpet zinnia, petunia, coleus, Spanish flag and vinca.
For starters, the butterfly bushes I have seen in Philadelphia area always have butterflies hovering over the blooms. They make a real sweet garden.
Rose White, author of Easy Gardens Volume 13 -
Bird Sanctuary Plus Butterfly and Hummingbird Gardens