How to Grow Showy Milkweed

Butterfly Magnet With Ornamental Value

Closeup of showy milkweed flower head.

Ethan R./Getty Images

Showy milkweed can help you put on a show in your yard in two respects. First of all, it bears lovely flowers that are worth growing for their own sake. But, secondly, it is also a great plant for attracting butterflies (as well as hummingbirds), those wonderful creatures that put on quite a show of their own. The flowers are succeeded by striking seed pods (up to 3 inches long). These pods split open at maturity to reveal the seeds within. A cotton-like substance is attached to the seeds, allowing them to be spread by the wind. When the stem of showy milkweed is broken, a milky sap (latex) runs out of it, accounting for the common name "milkweed." The leaves are large (up to 8 inches long), oval, bluish-green, and have prominent veins.

Showy milkweed resembles common milkweed, but it can be distinguished from the latter in two ways:

  • By its flowers: The star-shaped flowers are larger, and there is more space between the individual flowers in the flower head (or "umbel," which measures 3 inches across), making them stand out in a showy fashion (thus the common name)
  • By the presence of tiny "hairs" on the plant

Showy milkweed is perhaps most valued as being a host plant for the larvae (caterpillars) of monarch butterflies. Learn how to give showy milkweed the optimal conditions that it needs to put on a spectacular show in your landscape.

  Botanical Name  Asclepias speciosa
  Common Name  Showy milkweed
 Plant Type  Herbaceous perennial
 Mature Size  1 to 3 feet tall
 Sun Exposure  Full sun
 Soil Type  Average fertility, average to less than average water needs, well-drained
 Soil pH  Not fussy about soil pH
 Bloom Time  May to June
 Flower Color Rosey-purple and pink
  Hardiness Zones  3 to 9
 Native Area  Western North America

How to Care for Showy Milkweed

Showy milkweed is easy to grow. It tolerates drought and soils that are low in fertility. In fact, it may perform better in such ground than it does in soils that are wet and very fertile.

Since the plant will self-seed, some gardeners may find it a bit too easy to grow. There are surely better-behaved plants to grow in a mixed flower bed than showy milkweed. But it does not spread as much as the common milkweed. Moreover, it is easy to check the plant from spreading: Simply cut off the seed pods before they open. But if you have the space to permit showy milkweed to propagate itself, avoid taking this step: The seed pods add further interest and are useful in dried flower arrangements.

Once the plant becomes established, avoid trying to transplant it, since showy milkweed has a deep taproot. At planting time, select a spot for it in the landscape where you know you will want it to grow for several years.

Light

Showy milkweed blooms best if given full sun.

Soil

The main soil requirement for showy milkweed is good drainage.

Water

Do not overwater the plant once it is established. Showy milkweed prefers a soil that is somewhat on the dry side.

Fertilizer

There is no need to fertilize showy milkweed. In fact, too much fertilizer may result in underperformance.

Varieties of Milkweed, Related Plants

Asclepias is only one of many genera that belong to the Apocynaceae family. Other members of the family include:

  • Dogbane (Apocynum cannabium)
  • Blue star (Amsonia tabernaemontana)
  • Oleander (Nerium oleander)
  • Rocktrumpet (Mandevilla x amabilis)

Even within the Asclepias genus, there are many other species. They come in different heights and colors. Examples include:

  • Common milkweed (Asclepias syriaca): 2 to 4 feet in height; pink-purple
  • Butterfly weed (Asclepias tuberosa): 1 to 2 feet in height; light orange
  • Swamp milkweed (Asclepias incarnate): 4 to 5 feet in height; mauve, pink, or white
  • Sandhill milkweed (Asclepias humistrata): 1 to 3 feet in height; pink, lavender, or white

Toxicity Warning

Most species of Asclepias are poisonous to humans and pets. Deer pests usually leave them alone for this reason. Nevertheless, as is often the case with poisonous plants, those trained in herbal remedies have found a number of medicinal uses for them. Milkweed plants have traditionally been used to treat:


  • Colic
  • Diarrhea
  • Rash
  • Snakebite
  • Sore throat
  • Swelling