The bright orange umbels of Asclepias tuberosa (Butterfly Weed) is a familiar sight and is the best known member of the milkweed family. Hardy from zones 4-9, it is slow to foliate in the spring so you might want to leave the stems as a reminder until the new leaves emerge.
This Asclepias blooms on two to three foot stems in early June and on into July, if deadheaded,. The narrow leaves spiral up the hairy, stiff stems. If the flowers are left on the plant after blooming, additional interest is provided by the spindle-shaped seed pods which split open when ripe, releasing numerous silky-tailed seeds for dispersal by the wind. If you do not wish to be the recipient of innumerable seedlings, these pods must be pruned off before they split. These pods are also useful in arrangements.
As a perennial with a deep tap root, Asclepias tuberosa is drought-resistant and thus a valuable plant for the sunny dry garden, prairies, and naturalized/native plant areas. It is also perfect for a butterfly garden since the flowers are a nectar source for many butterflies and the leaves are a food source for monarch butterfly larvae (caterpillars). For those who can’t abide orange, there are now cultivars such as ‘Hello Yellow’, a golden yellow, that is slightly shorter than the species and ‘Gay Butterflies’ a mix of yellow, orange, and red-flowered forms.
Butterfly Weed combines well with yellow Rudbeckia fulgida ‘Goldsturm’ as well as some of the Rudbeckia species that are found in meadows and prairies. For an eye-opening combination, plant Larkspur with it. The combination of orange golden yellow and purple is smashing.
Asclepias incarnata (Swamp Milkweed), hardy in zones 3-7, is another useful garden species with lovely rose-pink umbels on three to four foot stems. Like Asclepias tuberosa, it has a deep taproot and is late to emerge in the spring. The flowers have a faint vanilla scent that attracts butterflies, particularly Monarchs. The stems are full of milky sap so it is best to wear gloves when cutting it back in late fall or early spring. As the common nameimplies, this Asclepias performs best in moist soil but will also do well in soil that receives average moisture and is well-drained. There are two pink cultivars,‘Cinderella’ and ‘Soul Mate’ but I see little difference between them and the species. There is also a white cultivar named ‘Ice Ballet’. As a native of wet meadows and prairies, Asclepias incarnata combines well with other natives such as Eupatorium fistulosum (Joe Pye Weed) and Aster novae-angliae (New England Aster).
If you are looking for a native perennial for inclusion in a butterfly garden or a sunny moist garden, look no further. Asclepias should be your plant of choice.