Symphyotrichum Species, Michaelmas Daisy, New York Aster

New York asters and their hybrids are the best-selling asters in the USA, widely sold along with fall mums. They vary tremendously in hei...Read Moreght, from 6" dwarfs to giants over 6' tall. They also come in a tremendously wide range of colors, many in shades of pink or violet-blue but also white, purple, lavender, and ruby red.

However, many of them spread aggressively, and they are commonly troubled by rust, mildew, and verticillium wilt, which not only disfigure them but also affect their winter survival.

In 2013, the Chicago Botanic Garden published a comprehensive evaluation of 119 asters, written by Richard Hawke, to identify outstanding performers for midwestern gardens. http://www.chicagobotanic.org/downloads/planteval_notes/no36...

They planted five plants of each of 62 New York aster varieties. Only 18 varieties had at least one plant survive four years on their test plot. This was not due to hardiness issues, as the mildest winter had the most extensive attrition.

They concluded that most of these can be recommended only as seasonal annuals rather than long-term perennials in northern gardens. This agrees with my own experience and observations.

Of the New York asters, only two, 'Climax' and 'Rosenwichtel', were rated 'Good'.

Asters whose performance rated "excellent" included aromatic aster (S. oblongifolium), Tatarian aster (A. tatarica), heath aster (S. ericoides), calico aster (S. lateriflorum), and white wood aster (S. divaricata).

Personally, I don't much care for the last two, and from personal experience I can also recommend turbinate aster (S. turbinellum), smooth aster (S. laeve), and some selections of New England aster (S. novi-angliae).

In US commerce, New York asters, especially the short forms, are most commonly labeled "Aster dumosus", which, though botanically incorrect, has to be considered a synonym.