I have long admired Amsonia, especially when grown en masse. These perennial herbaceous plants bloom small blue “stars” in the spring, provide wispy green foliage in the summer, and turn a solid gold or orange color in the fall. Most are native and there are several cultivars and hybrids. Mt. Cuba Center in Delaware just published a report on their 10-year amsonia trial of 20 different types of plants, including one non-native for comparison. The 16-page report is available for download here.
Also known as “bluestars,” these perennials look like two to three-feet shrubs in the summer. They are native bee habitats, support early season pollinators, and serve as host plants for several species of butterflies and moths. Like milkweeds, these plants produce a milky sap that deters deer.
Spring Sky, photo courtesy of Mt. Cuba Center
During the trial, the plants were virtually pest and disease free. They were grown in part to full sun on average soil and given minimal care. Supplemental water was only provided during the first year to encourage plant establishment.
The plants were rated on a scale of 1 to 5 with 1 being very poor and 5 being excellent for habit, vigor, and floral display. Not one rated a 5, but almost every plant in the evaluation was considered a top performer. The report provides a chart with the ratings, bloom time, floral display, size, foliage texture, and growth habit. The report also provides a 2023 bloom times chart as some plants bloom as early as mid-April and as late as June.
Short Stack, photo courtesy of Mt. Cuba Center
The two top performers are Amsonia ciliata ‘Spring Sky’ at 4.9 followed by A. tabernaemontana ‘Short Stack’ at 4.8. A. ciliata ‘Spring Sky’ or fringed bluestar reaches 2 feet high, blooms in mid-April to late May, and has finely textured foliage. ‘Short Stack’ is considered dwarf at 2 feet, blooms from mid-April to late May, and has more coarsely textured foliage.
The trial demonstrated that Amsonia are beautiful, easy to care for plants with three season interest. Like other perennials, they take time to get established.
This is the type of plant that attracts your attention in the fall with blazes of gold color and you think to yourself: Darn, I should have planted amsonia in the spring. So before the season starts this year, buy a few from your local garden center or check out the resources below. These companies were not in the report and do not imply a Mt. Cuba Center endorsement.
Plant Delights Nursery
Bluestone Perennials
American Meadows
Burpee
Izel Plants
