Amsonia hubrichtii, (pronounced am-SO-nee-yuh hew-BRIK-tee-eye) is flowering right now. This Arkansas native’s soft blue flowers are held at the top of tall stems that waft gracefully on the breeze. Leaves are narrow, leading to the common name Threadleaf Blue Star. Its fine, feather-like texture contrasts well with broad-leaf perennials like Black-Eyes Susans or Coneflowers. It also looks pretty when planted next to burgundy foliage plants like Ninebark, Smokebush, or Loropetalum.
While the spring flowers are pretty, Amsonia’s best season is fall. Those narrow leaves turn a golden yellow that glows in sunlight. For maximum impact, pick a site where the late afternoon sun provides a backlight.
Amsonia is undemanding. Give it full sun or mostly sun and it will be happy in zones 5-8 . Too much shade or excess water will cause it to flop. In rich soil, it may grow so tall that it opens up in the center in late summer. It takes at least a year or two for Amsonia to reach its potential. Don’t pull it up prematurely. Mature plants will reach heights of three feet, with a equal spread. Prevent the flopping or center separation by pruning it back to a height of six inches immediately after flowering ends. Cut to ground level just before spring growth commences.
Amsonia hubrichtii was the Perennial Plant Association’s “Plant of the Year” in 2011. Amsonias look great planted in masses. Flowers attract butterflies, and deer don’t seem too interested.
The blue flowers of Amsonia float at the top of thread-like foliage.
This Amsonia is just beginning to show hints of fall. In a few weeks, it will be a mass of butter-yellow leaves.