(Editor's Note: This article was originally published on September 9, 2009. Your comments are welcome, but please be aware that authors of previously published articles may not be able to respond to your questions.)
A few species, varieties, and cultivars of bluestar are commonly available and are choice plants for gardens in most parts of the United States and other temperate regions of the world. Selections are available that are hardy to Zone 4, and many are tolerant of extreme heat and drought. As a group, they are not picky about soil composition and are unusually long-lived and dependable garden plants.
Bluestars have alternate, entire leaves that range according to species from broadly ovate to linear and needle-like. Like other members of the Apocynaceae (dogbane family), they have a milky sap that deters deer and other mammals from eating the plants.
Bluestars have several characteristics that make them ideal additions to the garden and natural areas. In spring for about two weeks, the end of each stem is covered with clusters of blue to white star-shaped flowers. Flowers emerge from the stem with a funnel-shaped corolla, but at the end of the corolla they flatten out to form five sharply pointed petals looking for all the world like a blue star. Following the bloom, seeds are formed in cylindrical capsules.
Amsonia is especially attractive when planted enmasse. In spring, the flowers steal the show, but the attractive foliage holds its place throughout the summer. Remaining largely pest and disease free, bluestar provides an attractive background for other plants. Some, such as A. tabernaemontana have a commanding presence in the garden and function as shrubs. Others, such as the finely textured A. hubrichtii bend and sway in the slightest breeze and behave more like ornamental grasses. Still other species can be effectively used as groundcovers.
Kinds of Amsonia
The most widely known and commonly grown member of the species is A. tabernaemontana (eastern bluestar or blue dogbane). Native to eastern North America, it grows 2΄-3΄ tall and has relatively large narrowly ovate leaves that are 6" long and 2½" across. These bold-textured plants can make a commanding presence in the garden and are available from several vendors.
Amsonia illustris (Ozark bluestar or shining bluestar) occurs naturally in Arkansas, Kansas, Missouri, Oklahoma, and Texas and is very similar to A. tabernaemontana. As its common name suggests, leaves of this species are glossy. It, too, is available at a number of nurseries.
Amsonia hubrichtii (thread-leaf bluestar or Arkansas bluestar), native to the Ouachita mountains of Arkansas and Oklahoma, is the finest textured of the lot. Up to 50 stems can be found on mature plants, and each one is clothed with threadlike leaves closely spaced up the length of the stems. Like the other species, it blooms in spring and produces clusters of light blue flowers for two to three weeks. Foliage stays green during the summer, but in fall it turns into a dazzling golden mass for about a month. Order this species from a variety of nurseries.
Amsonia ludoviciana (Louisiana bluestar) was at first thought to be native only to Louisiana, but has more recently been found in Georgia, Mississippi, and South Carolina. Leaves have white wooly undersides. This species can be found at a few specialty nurseries.
Amsonia ciliata (fringed bluestar), so named because stems and leaves are lined with a fine fringe of hair, is at home sandy soils of Alabama, Arkansas, Florida, Georgia, North Carolina, South Carolina, and Texas. This species has linear leaves that are not as threadlike as A. hubrichtii. A variety of this species has recently been marketed by Plant Delights Nursery (A. ciliata var. tenuifolia ‘Georgia Pancake'. This diminutive form, stretching the native range of the species into Texas, Mexico, and Missouri, is useful as a groundcover plant. Dave's Garden Plantscout lists a few sources.
Amsonia peeblesii (Peebles' bluestar), from Arizona and A. jonesii (Jones' bluestar) from Arizona, Colorado, New Mexico and Utah, are excellent choices for gardeners in arid regions though they may be hard to find.
The Amsonias hybridize freely, so gardeners who grow more than one kind may find hybrids popping up in their gardens. Furthermore, taxonomists with their lumping and splitting tendencies sometimes split a species into more than one based on similar characteristics or group them together for the same reason.
These tough, long-lived perennials are easy to grow. Give them as much sun as can be managed. In full sun they will grow strongly and not require staking as they might if grown in shadier sites. Almost any garden soil will work, and most are extremely heat and drought tolerant.
Unlike many clumping perennials, bluestar does not die out in the middle and require division on a regular basis. As a matter of fact, the gardener would do well to plant it where it will stay, for the woody root mass is hard to dig up once established. About all the maintenance that is needed is a yearly cutting back of dead stems before new growth begins in spring.
Propagate bluestar from seeds following cold stratification or from cuttings taken in early summer. Plants grown from cuttings ensure that the new plants will be true to form. Seedlings may show some variations.
Look for a bluestar that is native to the area in which you live. Plant it in the garden, and water well until it becomes established. Then sit back and enjoy their carefree beauty for many, many years-perhaps for the rest of your life.
Thanks to Victorgarden for the image of A. hubrichtii and to RubalnMS for A. ciliata.