Asclepias Tubersosa, Native Milkweed
The Asclepias tuberosa, a native milkweed, is the Garden Club of America’s “2014 Plant of the Year.” This plant will be awarded the Montine McDaniel Freeman Medal on May 9, 2014 at the GCA Annual Meeting in New Orleans, Louisiana. Each year the medal is awarded to a native plant “that is under-utilized but worthy of preservation, propagation and promotion.” A committee of nationally renowned horticulturists and experts in the nursery trade make the selection from the plants nominated by GCA members.
(photo left by Carolyn Fannon and right by Thomas Muller)
The Asclepias tuberosa, a native to Texas and much of the United States, is a bushy perennial prized for the beauty of its large clusters of bright-orange flowers. The brilliant, long living flowers are a great addition to any landscape. Once established in a well drained, sunny location, it is long lived – around 20 years. The nectar attracts a wide variety of butterflies and countless beneficial insects and pollinators. However, its greatest value is serving as the larval host plant to the endangered monarch butterfly that migrates throughout much of the United States as it travels from Mexico to Canada each year. This plant is a perfect example of why some plants are critical to our landscapes well beyond their ornate qualities. People might confuse this plant with the tropical milkweed, A. curassavica, which is easy to propagate and commonly sold in most nurseries.
Asclepias tuberose is at risk of extinction in some areas of the country although it grows in a wide variety of soils, thrives in less than ideal conditions, has a long bloom period, and does not spread aggressively or contain the milky sap of most milkweeds. With raised public awareness of the environmental benefits and culture requirements, it is hoped that this trend can be reversed.
Propagation of this long taprooted plant can be a challenge since it does not do well in containers and the fresh seeds require a period of cool, damp stratification. Packets of seeds can be found in stores and are widely available through mail order. You can sow seed in the fall or spring, but they need a season of cold weather before they will produce blooms.
Dr. Malcolm Vidrine, the author of The Cajun Prairie, shared his propagation techniques:
I do have suggestions for growing milkweeds in general based upon my experience in Louisiana.
1.) Grow plants from wild or healthy stock collected as close to your location as possible--the typical mantra of less than 50 miles in radius is too far in my experience.
2.) Seed collected can be stored in the refrigerator in dry paper until 6 weeks prior to planting (I do this for Mardi Gras celebration). Remove seed and cold moist stratify (cms) seed in damp sand for 6 weeks in the refrigerator prior to planting. When you remove the seed from cms and add water, the viable seed float--making them easy to remove with a spoon and plant in good potting soil (This is my Easter entertainment). Plant in protected area indoors for highest survival rate--seedlings appear as early as in one week. With the appearance of the true leaves (ca. 3 weeks), move the plants into much larger containers (I move them to 5-10 gallon pots with plenty of room for roots to develop) and grow them for one year. In the winter, you can move the plants to any suitable location. You can even divide the roots into pieces ca. 2 inches in length and multiply your plants. Be prepared to lose up to 50% of your plants due to a variety of stresses in moving them from one location to another.
3.) I have 15 year old Asclepias tuberosa that can be dug up and propagated by root divisions as above. I have good luck rooting cuttings in early spring. So if there is a mature plant in your area, you can monitor it for seed or make spring cuttings for rooting (remove nearly all the leaves and any flower buds and bury ca. 3 inches into the soil) or dig a portion of its root system and grow plants from the root cuttings.
The combination of beauty, hardiness and environmental value make this a perennial plant that gardeners and naturalists across the country can grow with pleasure and satisfaction knowing they are helping not only the monarch butterfly population, but the beneficial insects and the countless birds and wildlife that depend on these insects for food.
by Doris Durbin Heard
The Garden Club of Houston