Asclepias, pronounced as-KLEE-pee-as, is a genus of North American native flowering plants, commonly known as milkweeds, that include over 100 species of hardy perennials that are fragrant, colorful, and easy-to-grow. The aromatic flowers of milkweeds are a favorite of butterflies and hummingbirds, and many species are used for butterfly gardens and for monarch waystations.
Asclepias plants are an important source of nectar and food for all sorts of pollinators including the beloved monarch butterfly who lay their eggs underneath the leaves. Named for the Greek god of healing, these perennials have a long history of medicinal usage and were used by Native Americans and early European settlers in North America to remove warts and to treat dysentery, typhus, and asthma.
More Information About Asclepias
Asclepias plants are popular perennial flowering plants that attract butterflies with their brightly colored flower clusters, hence the common names butterfly weed and butterfly flower. The flowers, leaves, and stems of this perennial wildflower are toxic, but not to butterflies or their larvae. Butterflies and other herbivorous insects that ingest asclepias nectar or leaves store the toxins in their bodies becoming toxic to any birds that subsequently snack on them. Monarch butterfly larvae feed almost exclusively on asclepias leaves.
The brightly colored flowers are also popular with hummingbirds. We have collected a few special asclepias selections hoping that gardeners will broaden their botanical horizons with a variety of butterfly milkweeds. Many asclepias species are North Carolina native plants for those of you inclined to favor them.
Some asclepias are drought-tolerant and prefer full sun and well-drained, somewhat dry soil, while others require saturated soils or standing water. Some are tough, low maintenance plants which require no supplemental irrigation, while others prefer moisture, which makes them perfect for rain gardens. Some milkweed plants are also salt tolerant.
Broken stems will produce a milky latex sap that is a skin irritant to some so take care when pruning milkweed. The attractive, long-lasting flowers of asclepias are followed in the late summer by spindle shaped seed pods that split open to release dandelion-like seeds attached to a fibrous parachute.
How to Grow and Care for Asclepias (Milkweed)
Where to Plant Milkweed
Asclepias can be planted anytime the ground is not frozen and when they can be irrigated until establishment.
When to Plant
Mid to late summer is the best time to plant, but asclepias can be planted in any season once the danger of frost is over.
Milkweed does best with at least 6 hours of full sun for the best flowers.
Good drainage is the key for those asclepias plants that prefer dry soils. Many milkweeds are salt and drought-tolerant and can be grown even in poor soils. On these species, crown rot can occur in overly wet, poorly drained soils or if planted too deep. Many species of asclepias prefer slightly acidic soil.
Asclepias Water Requirements
Adequate water is important until the milkweed plant has established roots. Keep the area moist but not too soggy. Again, good drainage is key. Once established, water moderately. Asclepias incarnata (Swamp Milkweed) prefers moist to soggy soils but can fare well in typical garden soils.
In the garden, asclepias should never need chemical fertilizers.
Pests & Diseases
Milkweeds are mostly pest free but can be susceptible to aphids. Crown rot can occur if dry-loving species are planted too deeply or over-watered in poorly drained soils. Milkweed is deer and rabbit resistant.
Asclepias species bloom throughout the spring and summer, depending on the species. Longer days are required to break dormancy.
Asclepias is poisonous to livestock so avoid planting in or around pastures. While asclepias is not dangerously toxic to humans, the sap can cause skin irritation for some so be sure to wear appropriate gloves when pruning.
Here are just a few of the possible companion plants to get you started. Visit our collection of butterfly attracting plants for a comprehensive list.
- Buddleia (Grand Cascade)
- Sedum (Back in Black)
- Baptisia (Lunar Eclipse)
- Muhlenbergia capillaris (Hairy Awn Muhly Grass)