Showy Milkweed

(Asclepias speciosa)

Showy Milkweed

Monarch butterflies, Idaho's official state insect, depend on host plants in the milkweed family for survival. Milkweed plants release a combination of chemical cues that lure female butterflies, who lay their eggs on the underside of the poisonous leaves.

After hatching, the monarch caterpillar’s only food is milkweed leaves. The milkweed toxins, which remain permanently in the monarch’s system, and the distinct pattern markings of the adult butterfly serve to discourage predators. Without milkweeds, these beautiful butterflies will completely disappear; their population has already dropped an incredible 90% over the past decade.

In spite of the name, most milkweed species are actually well behaved in a garden. They spread by seed, but a few, such as Idaho's native, Showy Milkweed (Asclepias speciosa), spread by runners. Showy Milkweed grows in the color garden at the Ella Street entrance to the Arboretum.

Milkweed lends itself to informal planting, either a sunny border or meadow, but will not tolerate shade. Depending on the location, milkweed can bloom from June through August, and adapt to a variety of soil types. Showy Milkweed grows 1½-3 ft. tall, with large oval, blue-green leaves. The blooms are eye-catching, with 4-inch clusters of fragrant, rose-colored, star-like flowers. Broken stems reveal a white, bitter latex sap.

To encourage monarch butterflies to stick around, plant some of their favorite nectar plants, such as Asters (Eurybia conspicua or Symphyotrichum laeve), Canada goldenrod (Solidago canadensis), and Wild Beebalm (Monarda fistulosa).

Showy Milkweed is found on page 168 of the KNPS publication, Landscaping with Native Plants in the Idaho Panhandle, available at local bookstores and the Bonner County History Museum.

Native Plant Notes are created by the Kinnikinnick Native Plant Society. To learn more about KNPS and the North Idaho Native Plant Arboretum, explore www.nativeplantsociety.org.