Generally, these require little care. They are vigorous enough to overcome caterpillar damage, so let them eat and enjoy the butterflies when they appear. Good pest resistance. Many of these species get larger than may be suspected at plant purchase. They need a lot of room to grow.
Some species are poisonous.
A very nice large flowering shrub for the late summer and early fall. Very good for a butterfly garden. Go to the Environmental Horticulture program page for further information.