The 2017 Perennial Plant of the Year, and Other Milkweeds You Should Know
Each year since 1990, the Perennial Plant Association has designated a “Perennial Plant of the Year.” The designation has become well known amongst growers, landscapers, gardeners, and others who eagerly await the announcement each year. Selection often launches the chosen plant into the mainstream, making it more widely available. While the association has often favored non-native ornamentals, for 2017 they have selected a native milkweed, commonly known as butterfly weed (Asclepias tuberosa).
Milkweeds (Asclepias spp.) are the required host plants for caterpillars of the monarch butterfly and thus play a critical role in the monarch’s life cycle. The loss of milkweed plants in the monarch’s spring and summer breeding areas is believed to be a significant factor contributing to the decline of monarch populations across North America. Over the past several years, the Xerces Society and others have been raising awareness of milkweed, working with growers to increase availability of seeds and plants, and urging gardeners in critical breeding areas to plant it. Though there are 73 known species of milkweed in North America, many of these species are rare, threatened, or endangered.
We can see why butterfly weed, with its broad range, vibrant orange flowers, and garden-friendly habit would be the milkweed of choice for Perennial Plant of the Year, but, like any plant, it needs the right conditions to thrive and may not be the best pick for every garden.
Read on to learn more about butterfly weed, as well as some alternatives you should know that may be better suited for your specific region or growing conditions. For more options visit xerces.org/milkweed/ where you can find region-specific milkweed guides.
2017 Perennial Plant Pick
Growing to a manageable height and spread of only 1’ to 2’, butterfly weed (Asclepias tuberosa) is easy to find a home for in even the smallest garden. Its unusual bright orange flowers are striking, especially when visited by green metallic sweat bees who are frequent visitors.
Butterfly weed is native to much of the lower 48 states and eastern Canada. It is not native to the northwest. Butterfly weed requires full sun, and dry well-drained soils. Butterfly weed does not perform well in heavy clay, richly amended garden soils or wet areas where its taproot will be prone to rot and the plant may not be reliably perennial. Its taproot makes it difficult to transplant, so be sure to pick a spot where you’ll want to enjoy the plant for years to come.
Makes a Splash in Most Any Garden
Despite its ugly name, swamp milkweed (Asclepias incarnate) is a knockout, and one of the easiest to grow milkweeds. Though the common name refers to the fact that it is often found in wet areas, at the edge of river-banks or low spots in meadows, it will tolerate a surprisingly wide range of soil types though may need supplemental watering in drier areas.
Swamp milkweed has a broad range, occurring in almost every state east of the Rockies from Northern Canada to Florida. Swamp milkweed grows to a height of 3’ to 4’ and will form small colonies where conditions suit. Though it prefers full sun it is one of the more shade tolerant milkweeds and can take partial sun. The soft pink, lightly scented flowers are large and showy, and the lance-shaped leaves are well enjoyed by monarchs. Some have observed that monarchs seem to prefer the leaves of swamp milkweed over those of butterfly weed when both are present.
Commonly Loved by Monarchs
Common milkweed (Asclepias syriaca) has a bad rap, as it’s known to be more aggressive than other milkweed species. It’s tendency to form colonies and readily re-seed can make it problematic in a garden setting. Still, studies have shown that it is the most frequently used host plant where its range overlaps with the monarch’s breeding areas, and as it’s rapidly disappearing from critical breeding habitat, it should be tolerated wherever it decides to pop up or embraced as a valuable addition to your garden. With one of the largest flower clusters and a tall sturdy stem, it can be a real “design feature” and should be considered a gift to your garden, rather than a nuisance.
The Star of the Show
For those lucky enough to live within the range where it grows, showy milkweed is arguably the most attractive of our native milkweeds. Growing to a manageable 1’ to 3’, it features a stout, upright stem with closely clasping, velvety, gray-green leaves. The real “star” of the show, however, is the showy spherical bloom. Unlike other milkweed species where the flower clusters display in a more open habit, showy milkweed blooms in tight clusters of prominently star-shaped flowers. Showy milkweed is beautiful enough to stop traffic, and more than a few passing monarchs.
Grows Where Others Can’t or Won’t
Naturally occurring on dry sites in plains, valleys, roadsides, and disturbed grounds in the west,- narrowleaf milkweed (Asclepias fascicularis) is drought and heat tolerant while being much-loved by monarchs. Often found in areas that may experience drought followed by seasonal flooding, it’s an ideal choice for rain gardens and rain catchment systems. As the common name implies, the plant features long, narrow, often heavily drooping leaves and a narrow stem. It often makes up for its wispy form by growing in dense clumps where its slender silhouette, in combination with several others, creates an airy mass topped by light pink flowers.
by Justin Wheeler, Web and Communications Specialist