Green Guide: Amsonia hubrichtii

Amsonia hubrichtii (blue star) is the Perennial Plant Association’s 2011 Perennial Plant of the Year. Native to central Arkansas, the plant produces soft, alternate needlelike green leaves during the spring and summer. During the fall the leaves turn a bright golden yellow. In April and May plants produce 2-to 3-inch clusters of soft blue, ½-inch star-shaped flowers on 3-foot tall stems.

Plants grow to 3 feet tall and wide in the landscape. The plant’s bright-yellow foliage makes it a good backdrop for fall-blooming perennials. It is hardy in USDA Hardiness Zones 4-9.

This southern native's leaves line the stems like bottle brushes. Surprisingly, they are soft as silk to the touch. After flowering, it quickly grows to reach a height of about 3 feet.

Amsonia adds a billowy, finely textured element to the landscape. It grows into a dense mass, much like a small shrub. The cool blue flowers can be useful in toning down adjacent flower colors. Arguably the best feature of blue star is its fall color; the entire plant turns a stunning shade of golden yellow.

Amsonia hubrichtii is native to fields and meadows in the Midwest.  It can be found growing naturally in Arkansas, Oklahoma, and Missouri.

In the Landscape
Amsonia thrives in most gardens with little care. It is low maintenance and easy to grow. Plant it in full sun or partial shade and moist soil of average fertility. If grown in too much shade or very rich soil, its habit will be open and floppy. This plant grows fairly large but it will not need to be divided for many years. Cutting the stems back to within six to eight inches off the ground after flowering will result in fuller growth.

University of Georgia horticulture professor Allan Armitage said the plant makes an outstanding display, particularly in the fall when the leaves turn a golden yellow color.

In the Nursery
Amsonia hubrichtii is available as #1 grade bare-root plants from Walters Gardens. The bare roots, which have five to eight eyes, can be planted into 1-gallon containers filled with a well-drained growing medium with a pH of 5.6-6.2. The bare root should be planted with the crown just below the soil surface.

After plants are watered in, the growing medium should be allowed to dry thoroughly between waterings. After new leaves have emerged, apply a water-soluble fertilizer with 50-100 parts per million nitrogen at each or every other irrigation.

Maintain a growing temperature of 55°F-65°F. Plants do not need to be pinched, but trimming or pinching back after flowering finishes increases plant density.

The only pest concerns are Mycosphaerella leaf spot and rusts. 


For more: Walters Gardens, www.waltersgardens.com. Perennial Plant Association, www.perennialplant.org.