Rain Gardens for Monarchs

By Chip Taylor, Lawrence, Kansas

Monarch, Julie Kenney

In addition to serving as catchments for runoff, rain gardens can be designed as habitats for wildlife. I work with monarch butterflies and direct a program known as Monarch Watch.

We have recently developed the Monarch Waystation Program, a new conservation initiative aimed at creating habitats for monarch butterflies. The justification for this program, largely the loss of habitats in the U.S., and additional information can be found here.

Rain gardens can be ideal habitats for monarchs if they incorporate the host plants needed for monarch larvae and the nectar bearing flowers for the adults. Below, you will find 6 milkweed species that serve as hosts for monarch caterpillars. All are native to the Midwest and are suitable for rain gardens. In addition, each is known to have colorful flowers that attract numerous butterflies and other pollinators.

Milkweeds can be started from seeds or can be planted as plugs. The latter is preferable as the plants will get a better start but starting plants from seeds or growing young plants indoors and planting the seedlings can be quite rewarding.

The above referenced propagation text describes stratification as a necessary condition for germination of seeds of most milkweed species; however, germination can also be induced by soaking seeds in hot water. To do this, place seeds in a jar, add hot water, let them sit for a day and then drain off the water and add more hot water each day for the next two days. On the fourth day place the seeds in flats with potting soil—making sure to cover the seeds with 1/4 to 1/2 inch of the soil.

The milkweed species are arranged below on the basis for their tolerance of wet conditions or need for well-drained soils. The first species, Swamp Milkweed, is tolerant of wet conditions while at the bottom of the list, Butterfly Weed, requires well-drained soils. If I were to plant these species in the typical rain garden, I'd plant the Swamp Milkweeds in the center followed by each of the other species as I moved upslope with the Butterfly Weeds planted around the outer edge of the rain garden.

Swamp Milkweed: Asclepias incarnata

Perennial.
Height: 4 to 5 feet.
Does well in wet areas.
Flowers are bright pink and rarely white.
Good nectar plant for butterflies.
Lives 3-5 years.
Will self sow in wet habitats.

Sullivant's Milkweed: Asclepias sullivantii

Perennial.
Height: 3 to 4 feet.
Flower clusters are erect rather than nodding and vary in color from mixed white to pinkish to a deep purple.
Blooms June to July.
Good nectar plant for butterflies.
Forms clones but not aggressive.
Tolerates periodic flooding.

Common Milkweed: Asclepias syriaca

Perennial.
Height: 3 to 5 feet.
Flower clusters are greenish purple to dull purple with a pleasant
fragrance. Blooms June to August.
An excellent nectar plant for butterflies.
Forms small clones.

Whorled Milkweed: Asclepias verticillata

Perennial.
Height: 1 to 2 1/2 feet.
Flower clusters are greenish white to white.
Leaves are narrow and grass-like and whorled about the stem. Inconspicuous until it blooms.
Blooms June to August.
Attracts numerous butterflies and other pollinators.
Forms small clones.
Will grow in a wide range of soil and moisture conditions.

Green Milkweed or Green Antelope Horn Milkweed: Asclepias viridis

Perennial.
Height: 1 to 2 feet.
Commonly found in prairies and pastures with clusters of greenish to purplish flowers.
Nectar source for early season bumblebee queens.
Drought-tolerant.
Blooms from mid-May to June and declines in July and August.
Needs relatively well-drained soils.

Butterfly Weed: Asclepias tuberosa

Perennial.
Height: 1 to 2 feet.
Attractive prairie plant with clusters of brilliant orange flowers.
Extremely attractive to butterflies.
This drought-tolerant species blooms from June to September.
Needs well-drained soils.

For information on sources of seeds and plants, please visit Monarch Watch or contact us via email at monarch@ku.edu.