Gardening Articles: Flowers :: Perennials
Blue Star (page 3 of 4)
by Rick Darke
Two Other Garden Favorites
Downy blue star (A. ciliata) is native to sterile sandy soils in the southern states. Older references often list this species as A. angustifolia. The leaves are up to 1/2 inch wide -- not nearly as narrow as those of threadleaf blue star. Stems and leaves have a fringe of fine hairs that are particularly appealing when plants are side- or back-lit by the sun. The light blue flower clusters tend to be held higher above the foliage and are among the showiest of all blue stars. Typical height is 2 to 2-1/2 feet. For best performance, this species requires sharply drained, relatively infertile soil. Grow it in full sun or very light shade. It is hardy to zone 4 with some snow cover, and also has exceptional heat and drought tolerance. It is not well suited to the cool climate of the Pacific Northwest.
Fringed blue star (A. c. tenuifolia, also known as A. c. filifolia) is a lower-growing, finer textured horticultural variety of downy blue star. Some plants reach only 1 foot and have leaves nearly as fine as threadleaf blue star. Until recently, it was virtually unknown except to plant collectors, but it shows great promise for gardeners. Like downy blue star, this one is native to infertile sandy soils. It does best with very good drainage but also performed well in trials at Longwood Gardens when grown in loam.
Some Lesser Stars
For years, European gardeners have grown Rhazya orientalis, a native of Greece and Asia Minor that is so similar to Amsonia that some botanists prefer to call it A. orientalis. It is nearly indistinguishable from lower-growing forms of eastern blue star. A. elliptica, native to Japan, China, and Korea, has rich blue flowers but is largely untried here.
Other American species, though little known, have great potential as garden plants. Lustrous blue star (A. illustris), native to the Southeast, is similar to eastern blue star but has exceptionally shiny leathery leaves. Especially glossy plants offered commercially as eastern blue star actually may be lustrous blue star.
Louisiana blue star (A. ludoviciana), similar to eastern blue star, is found in southern Louisiana but has thrived for years in the Gladwyne, Pennsylvania, garden of Mary Henry, now open to the public as the Henry Foundation for Botanical Research. Far ahead of her time, Mary Henry collected native blue stars and grew more than a dozen kinds by the early 1940s.