(Whorled Milkweed) Create a Monarch Butterfly Oasis by adding Milkweed to your garden. Asclepias verticillata is a hardy perennial in zones 3-9. Planted in full sun to part shade locations, Whorled Milkweed grows 1-3 feet tall in some of the harshest places like sand, clay, or rocky soils. This native woodland perennial has thin, whorled leaves and small greenish-white flowers that are flat. This long-blooming plant blooms May- September and is a host plant for the Monarch Butterflies. From egg to caterpillar to butterfly, milkweed is an important piece of the full life cycle. Plant in mass or mix with other great Milkweed for a colorful habitat for butterflies.