Year of the Asclepias

Discover the Magic of Milkweed! The great thing about Asclepias (Milkweed) is that there are many different species to choose from, and all have a variety of benefits that add value to your garden. Spending time learning about the different options is the best way to identify and select the right milkweed to grow into a beautiful stand.

Overview and History

Asclepias is a genus of herbaceous, perennial, flowering plants known as milkweeds and is a member of the dogbane family, Apocynaceae. Named for their latex, milkweeds exude a sticky and milky substance where cells are damaged. They are found throughout North and South America with over 100 species native to the U.S. and several cultivated as ornamentals. Many milkweed species grow into established stands and spread very quickly.  

Both animals and humans use milkweed for many different purposes. Butterflies, including Monarch butterflies, rely exclusively on milkweed plants as a food source for their larvae, meaning that without milkweeds, there would be no Monarch Butterfly. Native Americans used stem fibers to make string, rope, and cloth, while some tribes used Common Milkweed (Asclepias syriaca) for medicinal purposes, such as using the milky sap to treat warts, ringworm, and bee stings.  

The great thing about Asclepias is that there are many different species to choose from and all have a variety of benefits that add value to your garden. Spending time learning about the different options is the best way to identify and select the right milkweed to grow into a beautiful stand.  

Most Popular Species of Asclepias

• A. asperula ssp. asperula (Spider Milkweed) – Grows ~3 feet tall. Rose-white flowers surrounded by green. Does not tolerate high amounts of vegetative competition.
• A. asperula ssp. capricornu (Antelope Horns) – Grows ~2 feet tall. White and green flowers with curled seed follicles that resemble antelope horns.
• A. cordifolia (Heartleaf Milkweed) – Grows ~2 feet tall. Dark red-purple flowers.
• A. eriocarpa (Woollypod Milkweed) – Grows ~3 feet tall. Flowers are pink, white, or cream-colored.
• A. exaltata (Poke Milkweed) – Grows ~6 feet tall. The flower color is white to cream, tinted with purple and green. Long-lived, but not aggressive.
• A. fascicularis (Narrow-Leaved Milkweed) – Grows ~3 feet tall. Flowers range in color from greenish-white to rose pink.
• A. hirtella (Tall Green Milkweed) – Grows ~4 feet tall. Flowers have tinges of white and purple.
• A. humistrata (Pinewoods Milkweed) – Grows ~1.5 feet tall. Pinkish white to pale purple flowers. Requires deep, well-drained sandy soil.
• A. incarnata (Swamp Milkweed) – Grows ~5 feet tall. Flowers are generally light pink to light purple. Prefers moist to wet soils.
• A. latifolia (Broadleaf Milkweed) – Grows ~3 feet tall. Pale green to yellowish flowers.
• A. purpurascens (Purple Milkweed) – Grows ~4 feet tall. Flowers have rose pink petals with purplish white horns.
• A. speciosa (Showy Milkweed) – Grows ~4 feet tall. Rose, pink-, and purple-colored flowers. Tolerates many soil types. Needs full sun.
• A. subulate (Rush Milkweed) – Grows ~6 feet tall. This shrubby, leafless milkweed bears leaves only after rain. Whitish-green flowers.
• A. sullivantii (Prairie Milkweed) – Grows ~4 feet tall. Similar to Common milkweed, but less aggressive. Pink flowers.
• A. syriaca (Common Milkweed) – Grows ~6 feet tall. Native to most of North America. Pink or purple flowers. Likes dry, sunny areas.
• A. tuberosa (Butterfly Milkweed) – Grows ~3 feet tall. Bright orange flowers. Likes sandy, loamy, or rocky limestone soils.
• A. verticillata (Whorled Milkweed) – Grows ~3 feet tall. Skinny “whorled” leaves. White flowers.
• A. viridiflora (Green Comet Milkweed) – Grows ~2 feet tall. Pale green flowers.
• A. viridis (Green Milkweed) – Grows ~2 feet tall. White flowers with rose or purple centers.

New Cultivars of Asclepias

A. incarnata (Swamp Milkweed) can be planted in a variety of garden locations. The flowers are pink and fragrant. There are three cultivars of this species:

• Cinderella has light and medium pink flowers. 
• Ice Ballet has white flowers. 
• Soulmate has medium and dark pink flowers.

A. tuberosa (Butterfly Milkweed) has bright gold and orange fragrant flowers. A good choice for sunny borders in the garden. Some cultivars available are:

• Hello Yellow has sunny yellow to yellow-orange flowers. 
• Western Gold Mix is a western Colorado native with orange flowers that is perfect for western gardeners with alkaline soil. 
• Gay Butterflies provides gardeners with a mix of orange, red, and yellow flowers. 
• Prairie Gold has beautiful golden-yellow flowers. This cultivar originated from a wild population in Indiana. 

Asclepias for Your Garden

Tropical Milkweed – Friend or Foe?

While milkweeds can be beautiful and beneficial, some are harmful to some animals and humans. Tropical Milkweed (Asclepias curassavica) can be host to a protozoan parasite (Ophryocystis elektroscirrha) that reduces body mass, lifespan, mating success, and flight ability of Monarchs. This attractive plant disrupts the butterfly’s instincts to breed, migrate, or overwinter.

Which Species Should You Grow in Your Garden?

A little research on which species you’re looking to add to your garden will go a long way. Your typical gardening considerations like water, sun, height, spacing, bloom time, or color considerations will continue to apply for milkweeds, but here are some additional things to consider when deciding which Asclepias are right for you:

• Species’ growth habit – Because many milkweed species grow quite quickly, know which is best for your area to help prevent them from taking over your gardens or nearby plants.
• Native status – Species that are native to your area are the typically preferred milkweeds, however, introduced species that are nonthreatening to native plants or ecosystems can coexist with the native plants. Know the status of the species for your region to prevent the expansion of harmful invasive species.
• Companion plants – Many different types of companions can be planted alongside milkweeds to maximize benefits. You can consider grasses for a beautiful meadow or meadowscape or add additional flowers that provide nectar for adult monarchs and other butterflies during breeding through migration.

Milkweeds can be started in the garden in a variety of ways. By seed, dormant roots, or live plants. They are low-maintenance, longtime bloomers that come back each year. The more plants you have, the higher chance you will be visited by Monarchs. Plant at least five individual plants in an area if you can.