Some plants win your heart through their beauty, others through their ease of cultivation, and still others through their ability to attract birds, bees, butterflies, and other pollinators. But milkweed (Asclepias) scores the perennial plant Trifecta. 1. It’s beautiful. 2. Depending on variety, it produces clusters of tiny pink, mauve, or pinky white flowers perched like a Tiffany brooch atop tall, stiff stems, or bright orange sprays of clustered blooms or even sprays of purple. It’s low-maintenance and deer-resistant. And 3. Milkweed is both habitat and food source to a host of fascinating critters.
“There’s a whole ecosystem that revolves around Asclepias,” says Cindy King, horticulturist and naturalist at The Mill at Kingstown. “It’s not just the Monarchs.”
Most people know that milkweed is the specific host plant of endangered Monarch butterflies, but in addition to Monarch caterpillars, milkweed attracts the milkweed leaf beetle (Labidomera clivicollis), the red milkweed beetle (Tetraopes tetrophthalmus), the milkweed tussock moth caterpillar (Euchaetes egle), the Eastern milkweed seed bug (Oncopeltus fasciatus), and red aphids (Aphis nerii) along with their predators: ladybeetles (Coccinellidae), in both beetle and red dragon-like larval stage. Interestingly, virtually all of the creatures that congregate on milkweed are red and black or orange and black, colors that advertise their toxicity.
“The insects get toxins from eating the milkweed plant,” explains Dr. Sara Tangren, formerly University of Maryland Extension, now Coordinator at National Capital PRISM. Milkweeds contain cardiac glycosides, which are toxic to humans in large amounts.
“Deer don’t go for them, which is really nice, because of the sap, but tons of wildlife goes to them,” agrees horticulturist Ruth Rogers Clausen, author of Deer Resistant Native Plants for the Northeast.
While the deer leave them alone, if you have Monarch caterpillars and other insects visiting what they view as a buffet, you will see some plant damage.
“People buy milkweed for the Monarchs and expect it to stay pristine,” says King. The likely reason is that most think of butterflies sipping nectar, but forget about the munching caterpillars, who are an earlier incarnation of the winged beauty.
“The caterpillars will do some plant damage,” Tangren says, “But it is not fatal to the plant, and you are rewarded with the beautiful butterflies.”
Milkweed gets its common name from the milky juice that oozes from cut stems, which can be a skin irritant, particularly if you cut the bloom for a bouquet. (Clausen recommends searing the cut end to prevent sap ooze). Milkweed is also sometimes called ‘silkweed’ for the silky threads attached to the large, tear-shaped seedpods in fall. Those silky threads are like eiderdown to hummingbirds.
“In spring, hummingbirds try to find that downy attachment on those seeds to line their nest,” says King. “On the inside, they like spiderwebs and soft things. There was a study on hummingbird nests I read once, and close to 40% had down from milkweed seed.”
There are several types of milkweed, most of which are North American natives. The varieties we see around here, some growing in the ditches along the road are: A. syriaca, with big leaves that look like big green tongues; A. incarnata, called swamp milkweed, which has smaller clusters of bright pink flowers and grows 5 feet tall; and A. tuberosa, most often called butterfly milkweed or butterfly weed, which grows 2-3 feet tall and is usually flame orange, though hybridizers have cooked up new colors for the garden. For example, K. van Bourgondien sells a butterfly milkweed mix that includes everything from creamy yellow through fire engine red to pink, purplish and almost white.
“’Ice ballet’ is dead white and they get fairly large, and they’re very fragrant,” notes Clausen. “If you want them to branch out, pinch them when they’re younger.”
Most are fragrant to one degree or another. The volunteer A. syriaca in my garden wafts perfume while in bloom, as do the fields of A. incarnata that was seeded in a meadow on a local farm. Despite the tuberosa’s common name (butterfly milkweed) all milkweed can host Monarchs and other butterflies, which makes them great plants for virtually any garden. While there is a ‘plant it and they will come’ aspect to native plants, putting them in clumps makes them more discoverable by the animals they host. King suggests having at least five in a clump, so the critters aren’t looking for a botanical needle in a haystack.
“Your milkweed goes further if you plant it in small patches,” she says. “If you’re putting in a few plants, I’d put two-to-three at one end, and two-to-three in another, and plant a lot of composite flowers around – Joe Pye (Eupatorium) and Echinacea.”
King says those other plants will also act as attractive pollinator and predator plants.
“It you tuck it in with other things, if you plant a batch of it, you’ll see tons of tussocks moths (caterpillars) and the milkweed beetles – they look like ash bugs,” she says. “I leave it undisturbed and just let the ecology unfold and watch. I take binoculars out so I can see them without getting into the middle of it.”
Milkweed is a snap to grow provided you match growing conditions to type. Swamp milkweed, (A. incarnata) is a ditch plant, which is what makes it a good plant for rain gardens since it not only likes moist soil it can tolerate some shade making plant location more versatile. Butterfly milkweed (A.tuberosa), which is drought resistant, likes full sun and very well drained soil.
“Tuberosa likes it moister in full sun but does well with taller grasses around it to give it a little dappled shade like in prairies,” says King, adding, “I love that orange color.”
And she suggests, bearing in mind spring hummingbird nests, gardeners leave the plants up throughout fall and winter, so the silky seed threads fall on the ground for nesting. It’s all connected.
Longtime journalist, essayist, and garden writer Nancy Taylor Robson is also the author of four books: Woman in The Wheelhouse; award-winning Course of the Waterman; A Love Like No Other: Abigail and John Adams, a Modern Love Story; and OK Now What? A Caregiver’s Guide to What Matters, which she wrote with Sue Collins, RN.
Nancy DiAngelo says
The milkweed stems from the previous season also provide nesting material for orioles. I watch them peel long strips off to weave their basket nests every spring.