Milkweed is known for attracting monarch butterflies (Danaus plexippus).There are over 200 species of milkweed but Asclepias tuberosa is commonly known as butterflyweed and butterfly milkweed, and rightfully so. The plant is an important host plant for monarch, grey hairstreak, and queen butterflies. It is also an important nectar source for several other butterfly species. While it is native to North America, cultivars have been developed for home gardens. Asclepias tuberosa is a terrific choice for any butterfly garden.
Recognizing Asclepias tuberosa
Native to North America
According to the U.S. Forest Service, butterfly milkweed grows throughout Ontario and Quebec in Canada. In the U. S. A., the plant grows naturally in all but the northwestern states. It is particularly common in the Midwest and Great Plains regions. In the wild, it grows in prairies, open woods, canyons, and hillsides.
Recognizing Asclepia tuberosa
Butterfly milkweed is a beautiful plant that is often grown in home gardens. Compared to other milkweeds that can grow quite tall, Asclepia tuberosa is fairly compact, growing to about 0.5 to 1 m in height.
The plant has a bushy appearance, with numerous stalks forming a clump. Each stalk has narrow oblong leaves and is often topped by several stems. Each stem may host a flower umbel. (An umbel is a cluster of small flowers atop small stems that are similar in shape to the ribs of an umbrella.) The large umbels on butterfly milkweed are often flat or very slightly domed. These provide a handy “landing pad” for butterflies to rest on while extracting nectar.
Butterfly milkweed blossoms are most often bright orange. In fact, one other common name for the plant is “orange milkweed.” However, the Lady Bird Johnson Wildflower Centre states that the flowers might also be red or yellow–and that yellow blossoms predominate west of the 100th meridian. Blossoms are usually 1 cm across, which is relatively large. (The blossoms on species like Asclepias syriaca and Asclepias incarnata are closer to 0.5 cm across.) There are usually about 25 blossoms in each umbel.
Asclepia tuberosa blooms from June through August.
Asclepia tuberosa in the Garden
Butterfly milkweed is easy to grow and care for. Cold hardy in Zones 3-9, it should be planted in full sun. While it prefers well-drained sandy soil, it will grow in any kind of soil, including gravel and clay. It’s drought-tolerant.
The website for the Master Gardener Program at the University of Wisconsin-Madison explains that Asclepia tuberosa has a long taproot and doesn’t transplant well. It’s best started from seeds or cuttings. It’s easiest to sow seeds directly into the soil in the fall, replicating the way the plant self-seeds in nature. If started indoors, seeds need to go through cold stratification for about a month. Cuttings should be started in the fall as well. Take 5 cm sections from the taproot of an established plant and plant the cuttings vertically.
It will take 2-3 years for butterfly milkweed to bloom. But once established, the plant will become thicker each year, and will last for many years.
The one issue that butterfly milkweed may have is aphids–in particular, oleander aphids. The tiny insects rarely harm their host plant and they are tasty food for ladybugs. But if an infestation is bad, aphids can be removed with soapy water or with a high-pressure spray from a hose.
Asclepia tuberosa and Butterflies
According to the Lady Bird Johnson Wildflower Center, Asclepia tuberosa is a host plant for three different species of butterfly larvae:
- Monarchs (Danaus
plexippus)
- The monarch is one of the best-known species due to its beautiful orange and black coloration and its annual migration. They are found from coast to coast in North America. The Canadian Biodiversity Information Facility reports that monarchs have been spotted at times “well beyond the northern limits of its foodplants.”
- Grey hairstreaks (Strymon
melinus)
- According to the Butterflies and Moths of North America website, grey hairstreaks are found throughout the United States, with the largest concentrations on the western coast and in the southeastern states. They are rarely found in Canada, except in the southernmost areas near the international border with the United States. Grey hairstreaks are bluish-grey with a tail and large red spots near the tail.
- Queens (Danaus
gilippus)
- The Butterflies and Moths of North America website describes queen butterflies as chestnut brown, with a black border around their wings and white spots. The underside of their wings has black veining as well. Queens are found from coast to coast in the southern United States. They have been known to stray as far north as South Dakota and New Hampshire.
In addition to being a food source for some butterfly larvae, Asclepia tuberosa also attracts many other butterflies with its rich nectar:
- Eastern tiger swallowtails (Papilio glaucus)
- Fritillaries (subfamily Argynninae)
- Other hairstreaks (subfamily Theclinae)
- Painted ladies (Vanessa cardui)
- Pipevine swallowtails(Battus philenor)
Butterfly milkweed has gorgeous, bright flowers; it’s easy to care for; and it attracts a wide range of pollinators, including several species of butterflies. Whether you’re planning a butterfly garden or just looking for a plant for your flower bed, butterfly milkweed is a terrific choice.
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