Whenever we talk about one of our favorite butterflies, the monarch, the next topic is always milkweed. As the host plant for monarch caterpillars and a potential nectar source for the adult butterflies, the milkweed (Asclepias) can be a great addition to a pollinator-friendly landscape.
Despite being beneficial for pollinators, some species common in the Midwest, in particular the common milkweed (Asclepias syriaca), can be quite weedy. For many gardeners, this species is too difficult to manage in the home landscape. There are, however, other milkweed options that are more manageable in beds and borders that are worth adding to your garden.
Species & Care | Planting | Insects on Milkweed | More Infomration
Suggested Species & Care
Butterfly Weed
Butterfly weed (Asclepias tuberosa) is a native Iowa perennial. It is typically found in prairie remnants and roadsides throughout the state. Butterfly weed has narrow, lance-shaped leaves, grows 2 to 3 feet tall, and flowers from June to September. The flowers are usually bright orange but are occasionally yellow. Because of a specialized pollinating mechanism, only a few pods develop on most plants. The pods are spindle-shaped, 3 to 5 inches long, and contain numerous silky-tailed seeds. Butterfly weed has a deep taproot. The stems of butterfly weed produce a watery translucent sap when cut rather than a milky sap common to most milkweeds.
Care
Butterfly weed is an excellent plant for perennial beds and borders. It is easy to grow, requires very little maintenance, and has few pest problems. Plants possess excellent heat and drought tolerance. Butterfly weed requires full sun and well-drained soils. It performs well in dry soils and poor, infertile soils.
Cultivars
A limited number of butterfly weed cultivars are available. 'Gay Butterflies' has blooms in shades of red, orange, or yellow. 'Hello Yellow' has bright, yellow flowers.
Swamp Milkweed
Swamp milkweed (Asclepias incarnata) is another native perennial. It is typically found in prairie potholes, at the edges of marshes, and in wet ditches. Swamp milkweed has 3- to 6-inch-long, lance-shaped leaves, grows 3 to 5 feet tall, and blooms from July through August. The vanilla-scented flowers are pale pink to rose-purple. The flowers are followed by 3 to 4-inch pods, which contain numerous plumed seeds. Stems and leaves exude a milky sap when cut or bruised.
Care
Swamp milkweed is an excellent perennial for low sites or other moist locations in the landscape. Plants tolerate short dry periods, but prefer soils that are consistently moist or wet. Swamp milkweed prefers full sun.
Cultivars
A small number of cultivars are available. The individual flowers of 'Cinderella' have pink to dark pink reflexed petals and pink to white crowns. 'Ice Ballet' is a white-flowering cultivar. 'Soulmate' has deep rose pink flowers.
Prairie Milkweed
Prairie milkweed (Asclepias sullivantii) is similar in appearance to common milkweed. (However, it is less aggressive and, therefore, a more manageable plant in the garden than common milkweed.) Prairie milkweed is native to Iowa. However, it is far less common than the previously mentioned species. It is typically found in prairie remnants, railroad rights-of-way, roadsides, and other undisturbed sites. Plants grow 2 to 3 feet tall and produce pale pink to pinkish purple flowers from late June to early August. Leaves are 1½ to 3 inches wide and 4 to 6 inches long. After flowering, 2 to 4-inch-long seed pods develop. Leaves and stems exude a milky sap when cut or bruised. Prairie milkweed is also known as smooth milkweed and Sullivant's milkweed. The plant is named after 19th century American botanist William Starling Sullivant.
Care
Prairie milkweed adapts to a wide range of soils. It performs best in moist, well-drained soils in full sun. Remove the seed pods before they split open to prevent the spread of the plant in the landscape.
Planting Milkweeds
Butterfly, swamp, and prairie milkweeds can be established by planting seeds, bare-root plants, or container-grown plants.
Milkweeds are fairly easy to grow from seeds, but seedlings are rather slow-growing and may take 2 to 3 years to flower. Sow milkweed seeds outdoors in fall. Lightly work up the soil, scatter the seeds over the prepared area, and then cover the seeds with approximately 1/4 inch of soil. The cold, moist conditions during winter break the seed's dormancy, allowing the seeds to germinate in spring.
Plant bare-root plants in early spring as soon as the ground is workable. Dig a hole and then place the dormant plant in the hole. The crown of the plant should be positioned ½ inch below the soil surface. Fill the hole with soil and gently firm the soil with your hands.
Plant potted milkweeds in spring after the danger of frost is past. Potted plants should be planted at the same depth as they were growing in their containers.
When planting milkweeds, choose your site carefully. Established plants are difficult to transplant.
Insects on Milkweed
Milkweed is the host plant for monarch butterflies but they are not the only insects found on these plants. When growing milkweed (especially common milkweed - Asclepias syriaca), gardeners typically can find at least 5 common species of insects on the plants.
While some of these insects can make the plants look pretty unsightly, they are typically not a problem long-term for the plants.
Monarch Butterfly Caterpillars
Monarch butterfly caterpillars may not be the most abundant insects on milkweed, but they are the best known. Monarch caterpillars start out very small after emerging from pinhead-sized eggs laid on the leaves by female butterflies. They have alternating yellow, white, and black rings around the body and a pair of long, thin, black tubercles at the front and rear. Caterpillars take 2 weeks or more to grow to 2 inche,s and then they perform the magic of metamorphosis, transforming from ugly caterpillar into pretty butterflies.
Milkweed Tussock Moth Larvae
Near the top of milkweed plants, you may find clusters of 10 or more milkweed tussock moth larvae. These communal caterpillars are also orange, black, and white, but where the monarch caterpillars are hairless, tussock moth caterpillars are nothing but hair. There are several long tufts of black hair at the ends and along the lower sides of the body, and 6 pairs of bright orange tufts stick awkwardly upward in the middle. Caterpillars are fully grown at only one inch. There are two generations each summer.
Red Milkweed Beetle
The appropriately named red milkweed beetle is the most common of many beetles that feed on milkweeds. These attractive insects are slightly more than one-half inch long and red with 11 black spots scattered along the back. The red milkweed beetle larvae live in milkweed roots from late summer until the following July. Adults aggregate on leaves and flowers and are very common in the second half of the summer.
Milkweed Aphids
While examining the milkweed plant for insects, look closely at the stems and undersides of the leaves, especially at the top of the plant. There you are likely to find one of at least 4 common species of milkweed aphids. The most frequently observed is the yellow oleander aphid. Large colonies of mixed sizes of these brilliant yellow insects are common. Look closer. Some aphids have wings, most don’t, and there may be ants tending the aphids.
Milkweed Bugs
From mid- to late summer, when the milkweed seed pods are present, you may find aptly-named milkweed bugs. The adults will be orange and black, but if you are there early in the development of the bugs, you will find the orange-red nymphs. Milkweed bugs feed on sap from the developing seeds. If you are saving milkweed seeds to propagate in your butterfly garden, the milkweed bugs may further reduce already-low germination rates.
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