Which Milkweed is Right For Your Garden?
The most commonly available milkweeds include four species that are native across a vast swath of the continent, from the Atlantic coast to the Rocky Mountains, and from the Gulf Coast to southern Canada. Some of these milkweeds prefer wet locations but others prefer dry places. So, wherever you live and garden, there is a milkweed that will be right for you!
Common Milkweed—Asclepias syriaca: Seen in meadows across the eastern part of the United States, the Common Milkweed is a robust-looking plant with white (to-pink, to-pale-lavender) bell-like flowers. Growing between three and five feet tall (maybe taller in good garden soil), it's best placed at the back of the border. It prefers somewhat moist soil and plenty of sun, and it would look great combined with any native Switch Grass, such as Panicum ‘North Wind’.
Swamp Milkweed—Asclepias incarnata: This milkweed has rose-pink flowers and grows naturally in marshes, making it ideal for a moist spot in your garden. It would also make a great addition to a rain garden (a wide depression that collects excessive rainwater, gradually letting it be absorbed into the surrounding soil).
There are three popular varieties of Swamp milkweed for you to choose from, all growing over three feet high for a good ‘middle of the border’ placement: Ice Ballet is a recent introduction that has pure white flowers. Soulmate and Cinderella are two other new cultivars that are both quite floriferous and have deep-pink flowers. Either one would make a wonderful planting companion for Ice Ballet.
Whorled Milkweed—Asclepias verticillata: Whorled milkweed has attractive white flowers in loose clusters which open in mid-summer. It is shorter than most milkweeds, no more than thirty inches high, and it will also tolerate partial shade.
Whorled milkweed is found in dry locations across the eastern half of the continent and so will do best in a dry spot in the garden.
Butterfly Weed—Asclepias tuberosa: Butterfly weed is known for its cheery upright-facing orange flowers in mid-summer, and now it is joined by a new cultivar called Hello Yellow. As the name suggests, many kinds of adult butterflies will visit your garden to sip the nectar of your Butterfly Weed flowers. In addition, the plants will also attract Monarch butterflies for egg-laying.
Like the Whorled Milkweed, Butterfly Weed needs a dry location near the front of the border. And, since both these milkweed species are shorter in stature, they make perfect garden companions, where together their colorful white, orange and yellow flowers will make a lovely contrast. Now complete the picture with the linear texture of some Little Bluestem grasses!
Tropical Milkweed—Asclepias curassavica: Tropical Milkweed, hails all the way from South America. In colder climates across the continental USA and Canada, this one is normally grown as an annual where it will bloom from June to October. (Some people have good luck over-wintering their Tropical Milkweed indoors on a sunny windowsill). Save your seeds from the previous year and then start them indoors about eight weeks before your last frost date.
Tropical Milkweed grows up to 3 feet high. It has blood-red flowers with yellow hoods which would look lovely with a Swamp Milkweed cultivar, like Ice Ballet .
Tropical milkweed is also a great lure for Monarch butterflies where they will readily lay their eggs.
A word of warning: it is important that we gardeners do not inadvertently disrupt the annual Monarch migration patterns northward by encouraging a late hatch. So PLEASE , if you want to grow the tropical milkweed, check the date by which the Monarchs would normally leave your area for their migration northwards; and at that time cut your Tropical Milkweed plants to the ground.
Our sister organization, High Country Gardens, carries milkweed species that are native to the western states.
Growing Milkweeds in the Garden
Is Milkweed a weed?
While the name milkWEED sounds as though these plants may be poised to take over your garden, most species of milkweed are actually very well behaved in a garden setting. And, if you are concerned about your plants self-seeding in unwanted places it's easy to remove the large seedpods just before they split open and release their seeds in the fall. And a few species, such as the western Showy Pink Milkweed— Asclepias speciosa—spread by runners and are best grown in a meadow.
Garden Design with Milkweed in Mind
Milkweeds lend themselves to an informal planting, either in a sunny border or in a meadow (which you mow back annually in the fall). Their strong texture always looks stunning in conjunction with the taller prairie grasses, such as Big and Little Bluestems, Switch grasses and Tussock grass.