Monarch Butterflies are drastically decreasing in numbers. Urban development and insecticides have lead to the decline of the Monarch’s habitat, the common/native milkweed plant (Asclepias syriaca). Iowa gardeners can help to re-establish habitats by planting milkweed and other nectar plants in our backyards.
The milkweed plant is key because it’s the only plant that the Monarch butterfly lays her eggs on, and the larvae/caterpillars will only eat milkweed leaves as they mature. Once the adult butterfly has emerged from the chrysalis, it will then eat nectar from a variety of plants.
How do I grow milkweed? This common native plant is a thin, tall (3 to 4 feet) summer bloomer. The flower cluster forms a globe atop the plant’s rigid stem with fragrant flowers in various shades of pink to purple. Milkweed actually grows as wildflowers in zones 3 through 9 in fields and along roadsides in Eastern North America. They grow best in full sun, well-drained soil and are a drought resistant plant, requiring no fertilizer because they tolerate poor soils. The native milkweed (Asclepias syriaca) spreads both via seeds and rhizomes, forming colonies and can be invasive. If you grow the native plant, you may wish to remove the seed pods before they open to discourage the seeds from blowing and spreading.
There are two other types of milkweed that are not as hard to control. The first is swamp milkweed (Asclepias incarnata). Its characteristics are similar to common milkweed, except that it requires moisture retentive or damp soil like a bog, and doesn’t spread as aggressively. The second is called Butterfly Weed (Asclepias tuberosa), which is quite different in habit and appearance. This plant grows between 2 to 3 feet and has bright orange flower clusters, blooming mid to late summer. Butterfly weed takes longer to establish and isn’t as aggressive, although it can reseed. In order to attract Monarchs to either plant, be sure it’s planted in an area protected from the wind.
Once the Monarch has emerged from its chrysalis, it is attracted to the nectar of other plants; favorites include Liatris, Asters, Marigolds, Coneflower, Black-eyed Susans and Salvia. Lists of butterfly plants are widely available online, and in books and articles.
Do note that the milkweed leaves are poisonous to pets and small children. It’s the plant’s toxicity that protects the butterfly since the toxicity passes into the butterfly making birds and other predators avoid the insect.
To see a live view of these plants, visit the Noelridge Park All America Selections Butterfly Garden throughout the summer. Mark your calendar for the first information session on the butterfly habitat plants from 5:30 to 6:45 p.m. on July 9. Linn County Master Gardeners will be there to answer all your questions and provide butterfly habitat information.
Becki Lynch is a Linn County Master Gardener.