Asters are one of the delights of the fall garden. But there are also asters that add color to the summer garden, even a few spring-blooming species. How to choose among all this horticultural richness? To help gardeners narrow down their choices, the Mt. Cuba Center in Greenville, Delaware, a non-profit organization committed to promoting the appreciation, use, and conservation of plants native to the Appalachian Piedmont region, conducted a three year performance evaluation of asters. Fifty-six commercially available species and cultivars were evaluated for three years and rated on floral display, winter hardiness, cultural adaptability, and disease and pest resistance. Plants were given minimal maintenance to simulate the kind of care they'd receive in most home gardens.
One of the things noted in the evaluation report is all the name changes that have gone on recently in the Aster clan. While "aster" is still considered a valid common name, it is, alas, no longer such a widely valid scientific one. Botanically speaking, Aster species are now only found growing in Eurasia. In North America, this easy to remember and spell generic name has been replaced with a host of names that will challenge the memories of even the most devoted gardeners, including Symphyotrichum, Ionactis, Eurybia, Seriocarpus, Doellingeria, Ampelaster, and Oclemena -- whew! But many nurseries and plant catalogs continue to offer these plants under their now outdated, but more familiar botanical names, or list both old and new.
No matter how you name them, the study identified 14 top-rated asters and 8 "honorable mentions." Although the plants were specifically evaluated for their use in the mid-Atlantic region, the best performing asters are also likely to be good choices for gardeners in many other parts of the country. One of the highest scoring was 'Bluebird' smooth aster (Symphyotrichum laeve, formerly Aster laevis), shown blooming with goldenrod in a fall garden. Covered with abundant violet-blue flowers with yellow centers in September and October, this vigorous aster is usually mildew free and rarely needs staking. Prairie aster (Symphyotrichum turbinellum) and 'October Skies' aromatic aster (Symphyotrichum oblongifolium 'October Skies') also received high marks.
To read about all the recommended asters, go to: Asters for the Mid-Atlantic Region.