Video Wednesday: Amsonia Plant Profile
Amsonia hubrichtii grows well outside of its limited native range (the mountains of western Arkansas) and is proven to be hardy in USDA Zones 4–9. This herbaceous perennial takes about three growing seasons to reach maturity and is long-lived. A mature plant will have about 50 stems and grows three feet high and wide. This species is also commonly called thread-leaf blue star or Arkansas blue star — or, simply, Amsonia.
It dies down in the winter and starts to re-sprout in April. It is deer-resistant and well-noted for providing three seasons of interest. In spring, there are clusters of pale-blue flowers. Then, in summer, it has copious amounts of feathery, apple-green foliage. Finally. it has brilliant, clear-yellow foliage for at least a month in autumn. It is most often planted because of this colorful display it provides from October into November.
You can prune the plant to about 12 inches high immediately after the bloom cycle has ended to encourage a fuller growth habit for the summer. The sap is sticky; so wear gloves when pruning.
It produces its best color when grown in full sun. However, it will tolerate morning sun and afternoon shade. Amsonia prefers moist, well-drained soil, but it can adapt to somewhat drier conditions once it has become established.
The best method for propagating Amsonia hubrichtii is by dividing the crown in spring. Softwood cuttings are also possible. Starting this species by seed has mixed results, because the seeds sprout erratically.
Amsonia hubrichtii is known for its effectiveness in mass plantings, informal borders, and naturalistic landscapes. I love seeing it planted along roadsides throughout the Mid-Atlantic states. One famous landscape setting is by the Capitol Columns at the U.S. National Arboretum in Washington, DC. It is a show-stopping display in mid-autumn with the purple aster blooms setting off the golden amsonia foliage.
Amsonia hubrichtii: You Can Grow That!