Seeds from this Asclepias stenophylla Slim leaf milkweed This plant has violet tinged white blossoms and is hardy in zones 5-9 and will bring more monarch butterflies than you can imagine. Believed to have naturally migrated from the western Ozarks, this plant prefers full sun and well-drained soils, often rocky or sandy rangelands or hillside prairies. These perennials grow 2-3 feet tall and can tolerate some pretty awful coastal clays that are sour bogs in winter and salty toast in summer. Quite a drought-tolerant plant I don’t think that I have ever had to water them.