Down To Earth Garden Club

Every year the Perennial Plant Association chooses a plant with outstanding characteristics upon which to bestow the title of Perennial plant of the year; sort of like Miss America with roots. Again like Miss America these plants tend to be robust, native or well adapted to regional gardens and hardy growers. The criteria on which this selection is made are:

•Suitable for a wide range of climatic conditions

•Low maintenance

•Pest and disease resistant

•Readily available in the year of release

•Multiple seasons of ornamental interest

•Easily propagated by asexual or seed propagation

This year the choice is Amsonia hubrichtii or Arkansas Blue Star. This Amsonia, as its name suggests, is native to Ouachita Mountains in central Arkansas. It is also said to grow wild in Oklahoma and Missouri. Hubrichtii was first collected in Arkansas in 1942 by Leslie Hubricht. Its preferred location is open fields and meadows

There are number of other species of Amsonia; sources list as many as 22. They range from ground covers to over 3 feet tall and grow so robustly that they can serve as bushes. Most are native to North America but Amsonia elliptica grows in Japan and Korea. It is rare in cultivation. The most commonly cultivated, Amsonia tabernaemontana, is a native Missouri wetland species that has naturalized from Texas, some of the Midwest through the south and as far north as Massachusetts. There are a number of cultivars of tabernaemontana; ‘Blue Star’ and ‘Blue Ice’ are two. ‘Blue Ice’ is a shorter version of tabernaemontana with more violet flowers. It is of unknown parentage.  ‘Blue Star’ is also a shorter cultivar and is thought to be a hybrid of another cultivar, A. tabernaemontana ‘Montana”.

 Although tabernaemontana is the easiest to find and the best know Amsonia, the Perennial Plant Association has given its nod to the less well known hubrichtii. Possibly this is because of the foliage. The leaf of Hubrichtii is the finest cut of all of the Amsonias. Its leaves, surrounding the stem, are needle like but fine and soft to the touch. In the fall the foliage turns a bright yellow making a stunning background to fall blooming perennials. Tabernaemonata has much coarser foliage and lacks the delicacy of hubrichtii. While it does turn yellow in the fall the foliage is not as brilliant as that of hubrichtii.

The Blue Star Amsonia plant  ranges from 2 to 3 feet in height and is very full and bushy. It has a spread of about 4 feet. The leaves are its most striking feature. They are up to 3 inches long and very fine and threadlike. They are packed densely along the stems and are a bright medium green in color.

Arkansas Blue Star produces a profusion of small flowers in 2-3 inch clusters.  The flowers are medium blue, and as its name suggests, star shaped. The flowers are said to lighten in the warmer part of its range. The blue color is deepest in the bud stage and can fade to almost white in bright sun. The flowers are produced from April, soon after the plant emerges from the ground, through May.

This plant is extremely robust and versatile. It is hardy through zone 4 but is not bothered by heat. It tolerates a wide range of soil conditions and is forbearing of less than ideal conditions, including low rainfall. It will also grow in fairly moist soil.                          

The plant needs no deadheading or pruning although cutting it back to the ground will result in a fuller specimen. Plants grown with too much shade will get leggy but, while it prefers full sun, it will tolerate some shade.  Even the deer and rabbits don’t bother it. Amsonia tabernaemontana is known as dogbane because it contains, as does hubrichtii, a milky substance that can irritate human skin and animals find it distasteful. Butterflies and moth however do not. They are its chief pollinators.

There are three ways of propagating Amsonia. Softwood cuttings may be taken in the early part of summer after the plant blooms. Root cuttings are also a possibility. Pieces of the fleshy root can be laid horizontally in a moisture retaining medium. The seeds germinate irregularly and must have a cold cycle….sometimes several.  Bottom heat is also suggested for better germination.  Division is possible but is difficult because of the woody nature of the roots.

Hubrichtii appears to have no accidental cultivars nor has it ever been part of a breeding program. Perhaps this lack of interest by commercial nurseries and plant breeders is why it has been so underutilized in the garden. Now that perennial of the year status has been awarded to the plant there is a chance that this will change.