Make way for monarchs and jazz up your garden by growing locally native species
Fine Gardening By Benjamin Vogt Issue #200 - June/July
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Monarch butterflies rely on milkweed (Asclepias spp. and cvs., Zones 3–9) as their primary host plant. As the monarchs’ western migration teeters on vanishing completely within years and the eastern migration faces large swaths of now-absent prairie, gardeners and conservationists can make a difference by planting more milkweed and the natural plant communities that grow along with it. Across the United States there are some 73 species in the Asclepias genus, native to practically every locale, with the greatest diversity in the Southern Plains and the Southwest.
It’s pretty amazing that we have as many milkweed species as we do, given how complex they are to pollinate. The process requires an insect to slip a leg into a very narrow slit between the flower anthers, extract a sticky, waxy ball of pollen, then reverse the process on another bloom. Occasionally, an insect loses a leg in the process or becomes permanently stuck in the flower.
When you grow milkweed, you may notice monarch caterpillars feeding alongside other species such as tussock moths, milkweed beetles, or milkweed bugs. Consider this exciting proof that your ecosystem is thriving. If you see yellow oleander aphids, don’t rush to spray the plant with water—you might also knock off a monarch egg or young caterpillar. Instead, strive to create a layered, diverse garden that supports beneficial predators that will control the aphids naturally.
When adding milkweed to your garden, try to stick with species that are native to your region. You are likely familiar with a few species already, such as the aggressive common milkweed (A. syriaca, Zones 3–9), which is widely distributed through eastern North America and the Midwest. These spread by rhizomes and are generally better suited to larger spaces where they can ramble. But there are also many better-behaved options with big native ranges, such as swamp milkweed (A. incarnata, Zones 3–9) for moist areas and butterfly weed (A. tuberosa, Zones 3–9) for dry ones. The following are some unique species you’re likely to find at specialty native plant nurseries, all suitable for a range of site conditions. Plant a few, and you can help rebuild monarch habitat at home.
Milkweed at a glance • Asclepias spp. and cvs.
Diseases: If plants exhibit symptoms of a pathogen infection, such as wilting or yellowing leaves, do not spray. Instead, remove and dispose of the affected parts to prevent the infection of healthy plants.
Conditions: Most milkweeds prefer full sun and well-drained soil, but some are adapted to grow in full to partial shade and moist to wet soil.
Grow it from seed: To help milkweed germinate, surface-sow the seed on weed-free garden soil in fall or early winter.
Photo 1: Benjamin Vogt Common milkweed A. syriaca
Photo 2 : Carol Collins Swamp milkweed A. incarnata
Photo 3: Jennifer Benner Butterfly weed A. tuberosa
Photo 4: Benjamin Vogt Showy milkweed A. speciosa
For fine foliage, plant whorled milkweed
Distribution
A. verticillate Zones: 3–9
Native range: Dry habitats such as open woods, pastures, fields, prairies, and roadsides of eastern North America.
You’ve probably seen whorled milkweed without knowing it’s a milkweed. It has thin, pinelike foliage that emerges before other species, making it a great host for early monarch migrants. It grows about 2 feet tall & wide, and prefers a hot, dry location in full sun. It will grow in almost any soil: clay, loam, sand, or gravel. Enjoy the brilliant cream flowers from mid to late summer, and expect the plants to move freely about your landscape in scattered patches for a wonderful, natural effect.
Photo: courtesy of Prairie Moon Nursery
Poke milkweed likes it a little shady
Distribution
A. exaltata Zones: 3–7
Native range: Shady, moist woodland edges, clearings, shores of the Midwest, Appalachia, northeastern United States, & southeastern Canada.
Poke milkweed reaches 3 to 5 feet tall and 1 to 2 feet wide. It grows best in morning sun, dappled shade, or open woodlands, and well-drained soil is a must. One of the more shade-tolerant milkweed species, it may hybridize with common milkweed if they are close together. While not as showy as other species, it nevertheless fills an important ecological niche in natural shade gardens.
The deep, rosy pink blooms of purple milkweed are perhaps the most beautiful of any milkweed species.
Distribution
A. purpurascens Zones: 3–8
Native range: Moist to dry prairies, meadows, & open woodlands of eastern North America
The plants grow 2 to 3 feet tall and wide and do best in moderately moist clay or clay loam in partial sun. (More consistent moisture is needed with more sun.) It’s not really aggressive, so be patient, as it may take several years to establish and bloom. It can be a bit finicky to maintain, so plant it in slightly different areas of your landscape to see which conditions it likes best.
Sources
Izel Native Plants, Washington, DC; 410-989-3721; izelplants.com
Joyful Butterfly, Blackstock, SC; 803-374-2591; joyfulbutterfly.com
Prairie Moon Nursery, Winona, MN; 866-417-8156; prairiemoon.com
Benjamin Vogt is the author of A New Garden Ethic and the forthcoming Prairie Up: An Introduction to Natural Garden Design. He is the owner of the prairie garden design firm Monarch Gardens, based in Lincoln and Omaha, Nebraska.
Distribution maps provided by John T. Kartesz, the Biota of North America Program (BONAP), Chapel Hill, North Carolina [Floristic Synthesis of North America, Version 1.0]