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What You Need to Know for Growing Milkweed Plants

Jule Romans has been gardening with native wildflowers for over 15 years. She loves to share knowledge about her favorite native plants.

Common Milkweed, Asclepias Syriaca

Common Milkweed, Asclepias Syriaca

Milkweed, or asclepias, was once considered an annoying weed. Now that the link between milkweed and butterflies has become common knowledge, Butterfly Milkweed and its relatives have become desirable garden plants.

These plants are known by many names. The most easily recognized varieties are:

  • Pink Milkweed (Asclepias incarnata)
  • Butterfly Milkweed (Asclepias tuberosa)
  • Common Milkweed (Asclepias syriaca)

There are other choices in milkweed too:

  • Prairie Milkweed (Asclepias sullivanti)
  • Showy Milkweed (Asclepias speciosa)
  • Whorled Milkweed (Asclepias verticillata)
  • Tall Green Milkweed (Asclepias hirtella)
  • Spider Milkweed (Asclepias viridis)

Popular Milkweed Types

Milkweed comes in several varieties, but the most popular are Butterfly Weed and Pink Milkweed. Pink Milkweed is sometimes called Swamp Milkweed, but it is the same plant. These two varieties produce the showiest flowers and the strongest nectar. They are ideal native plants to add to the home garden. Milkweed flowers will attract butterflies by the dozens.

Every gardener who wants to encourage butterflies should plant several stands of milkweed and let them spread. This is especially great for the garden that has a lot of free space. Milkweed will fill in large sunny spots very effectively.

Milkweed and Butterflies

Almost all asclepias (milkweed) plants produce a white, sticky sap that oozes freely when their stems or leaves are broken. This sap contains a semi-poisonous compound that can be toxic to animals when consumed in large quantities. Even in small amounts, the cardiac glycosides in milkweed will make birds and other smaller species quite sick.

It is this sap that is the key to the survival of the monarch butterfly. Monarch caterpillars will eat ONLY milkweed foliage. Monarch caterpillars cannot survive on any other plant. Monarch butterflies lay their eggs on milkweed plants after feeding on the nectar in their flowers. The caterpillars can safely grow to maturity on the asclepias plants. Predators will avoid both the plant and the brightly striped green/ black/white caterpillars.

Growing Milkweed in the City

Many gardeners grow Asclepias incarnata (otherwise known as Swamp Milkweed) in the city. In fact, this is the best place of all to plant milkweed. Butterflies need good places throughout urban areas so that they can feed and lay their eggs. Many butterflies die each year because they become trapped in cities, where few nectar or host plants bloom. Every small planting of milkweed can be a haven for butterflies. This will help them survive.

Milkweed is easy to grow from seed in small spaces. One gardener grows milkweed on a balcony. He has made a tremendous difference in his community. His example is a great one for other city gardeners who want to explore the benefits of native plants in urban or balcony gardens.

Growing Milkweed Plant Types

Below is a short list of some of the most popular native Milkweed plant types for home gardens. Native Milkweed is always the best choice.

Butterfly Milkweed, Asclepias tuberosa

Butterfly Milkweed, Asclepias tuberosa

Butterfly Milkweed (Asclepias Tuberosa)

Butterfly weed is the most popular milkweed for growing in the garden. Many people are not even aware that they are growing milkweed when they plant butterfly weed. Distinctive bright orange flowers top long stems that have slender leaves along their entire length. Butterflies do love this plant; monarchs love it most of all.

Originally, this native prairie flower was known as pleurisy root. That is because it was believed that the root would heal lung disease.

Milkweed Is Better Than Butterfly Bush

Unlike butterfly bush, Butterfly Weed is truly beneficial because it also provides a host plant for monarch caterpillars. Butterfly Bush (buddleia) will attract butterflies, but offer no support for them to lay their eggs. Unless there are host plants nearby, monarchs and other butterflies will not be able to lay eggs. Planting Butterfly weed helps adult butterflies, but more importantly, it also helps ensure future generations of happy "flying jewels."

Swamp Milkweed, Asclepias incarnata

Swamp Milkweed, Asclepias incarnata

Pink Milkweed, Swamp Milkweed (Ascepias Incarnata)

Contrary to what the name implies, Swamp Milkweed does not necessarily have to be in a wet location to thrive. If planted in regular garden soil, it can do very well with only occasional watering. Of course, the more water it receives, the larger and stronger it will grow.

Since this plant tends to grow 4–5 feet tall, many gardeners “pinch it back.” Pinching back is a technique of cutting a plants stems down several weeks before it begins to create flowers. This results in a bushier, shorter plant that is easier to keep in smaller spaces. This fabulous prairie flower is the favorite choice of monarch caterpillars because it has more tender leaves.

Common Milkweed, Asclepias syriaca

Common Milkweed, Asclepias syriaca

Common Milkweed (Asclepias Syriaca)

This is the original milkweed that was viewed as an obnoxious pest for so long. It does not have flowers that are as large or noticeable as the other prairie flowers in the asclepias category. However, it is a very strong plant that will thrive in dusty areas, such as near roadsides.

Common Milkweed will grow very tall, so it makes a better background plant, or meadow plant. Do not plant this variety in containers or try to transplant it. Common milkweed will create a six foot long taproot. If the root is severed while digging, the plant can die. If a container is too small, the root will become twisted, and the plant will not be as healthy as it could be in the ground.

Other Milkweed Types

Here's a brief look at some other milkweed types.

Prairie Milkweed (Asclepias Sullivanti)

This plant does best in wet meadows. It prefers moist soil. It does look similar to common milkweed, but it has smoother stems and much more showy flowers. Birds love Prairie Milkweed. It was named after the great botanist William Sullivant, who discovered it.

Showy Milkweed (Asclepias Speciosa)

Note the tight cluster of flowers on this plant. It makes very large flowering balls, that definitely catch the eye with their beauty. This prairie flower blooms in summer. It does very well in mixed plantings and small meadows. Showy Milkweed does not need a lot of water.

Whorled Milkweed (Asclepias Verticillata)

the leaves of this plant are arranged in a circle around the stem, giving the plant its common name. The flowers are small and greenish or white. they appear in flat-topped clusters, much like Queen Anne's Lace. This prairie flower will do best in a very sandy and dry location. Too much water and rich soil will likely cause it to develop weak stems and flop over.

Prairie Milkweed (Asclepias Hirtella)

Priairie Millkweed is also known as Tall Green Milkweed. This plant has hairy stems and flower stalks. The flowers are very small, but quite numerous. It will bloom from May to August. The mature plant will grow to about 1–3 feet tall. Height is a consideration to keep in mind when planting milkweed in the garden. This particular variety of milkweed is not as often used in gardens, but it has many benefits for native insects, including honey bees and bumblebees. It can blend in nicely within a stand of Butterfly Weed or Common Milkweed.

Spider Milkweed (Asclepias Viridis)

Spider Milkweed is also known as Green Milkweed. A distinctive characteristic of this plant is the margins of the leaves. They are a bit like waves. The flowers look white, but they have very small centers that can be tinges with pink or purple. Spider Milkweed blooms from late spring through about the middle of summer. It, like many milkweeds, prefers dry soils and open areas. It will often grow along roadsides in the United States.

Selected Sources

  • Missouri Department of Conservation. (n.d.) Field Guide: Asclepias hirtella.. <nature.mdc.mo.gov/discover-nature>.
  • Native Plants of North America. (2021). Lady Bird Johnson Wildflower Center. <Wildflower.org>.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.