Maybe you’re a more organized gardener than I am. Sometimes I’m unsure if a seedling I see popping up is something I intended to grow or just a weed. I’ve been watching such a plant all summer, wondering if it’s a tall interloper or an aster. Gardening takes patience, and I remember well the times I’ve hastily pulled up a “weed” only to realize it was something I planted on purpose, so I waited for most of the summer to find out. Finally, my mystery shoulder-height plant revealed itself to be the smooth blue aster ‘Bluebird’ as it burst into a cloud of pale lilac stars. (“Aster” is Greek for “star.”)
Cuttings from the writer’s collection display the wide range of color and form in the aster clan. (Photos by Stephen Orr)
Asters are a wide-ranging group of plants that are vitally important in my garden as one of the most vivid last hurrahs of flowers. They’re followed only by my hardy chrysanthemums, now in expectant bud.
The one challenge with this large group of plants is choosing which variety to grow. I’d say all of them, but I know we don’t all have the room. There are some 250 types of asters around the globe. Most of the varieties we buy at our nurseries are hybrids of our native Symphyotrichum novae-angliae (New England aster) or Symphyotrichum novi-belgii (New York aster). These include the taller species, which can grow up to six feet in some cases, or lower mounding selections like ‘Purple Dome’ that grows one to two feet tall. ‘Andenken an Alma Pötschke’ stands at about three feet and is famous for its unusual cherry-pink color.
Cerise ‘Andenken an Alma Pötschke’ mingles with pink dahlias and cosmos as frost approaches.
I should caution plant shoppers that asters have a lot of confusing names. Many varieties look alike, with composite, daisy-like flowers that make them difficult to keep straight — but don’t let that stop you.
The Aster genus was controversially split into two main categories in the 1990s (something many gardeners and retailers have resisted ever since). Aster now covers all asters from Europe and Asia, while the hard to pronounce and harder to remember Symphyotrichum mainly covers North American species. To make matters more confusing, other genera have been added, such as Eurybia (including wood asters) and Doellengeria (including flat-topped asters). Suffice it to say, unless you’re really into botany, it’s fine to select the colors and forms that appeal to you most and ignore the botanical vagaries.
Vivid ‘Raydon’s Favorite,’ an aromatic aster, leans out of the flower border in front of a taller pastel spray of sky blue aster (Symphyotrichum oolentangiense).
I love the blue and purple range most, particularly when grown together. Their ultraviolet colors seem to glow and vibrate as the sun goes down. Aster × frikartii ‘Mönch’ is very long-blooming and starts earlier than other asters. Aromatic aster ‘October Skies’ (S. oblongifolium) grows low and wide. Sky blue aster (S. oolentangiense) has an airy habit and makes a good see-through plant to put at the front of a flower bed even though it’s tall.
Our native white heath aster (S. ericoides) can be seen growing happily wherever it finds a toehold. This year we have a robust new clump growing as a skirt under an old log. We also have a volunteer of the white wood aster (Eurybia divaricata) in our semi-shade garden. It is one of the few asters that prefer part shade as opposed to full sun.
Asters, like most composite flowers, are pollinator favorites. Dozens of pollen-bearing flowers are grouped in the yellow center, surrounded by colorful ray florets that we think of as the “flower.”
I find that asters perform quite well in my free-draining sandy soil as long as I give them a top layer of compost and mulch several times during the growing season along with regular moisture, though they sailed through this year’s summer drought with no complaints. The dryness might also be keeping at bay fungal diseases like powdery mildew that can plague some New York and New England asters. If you have mildew one year, be sure to clean up all the dead leaves and dispose of them so the fungus doesn’t overwinter in your beds.
Tall arching stems of ‘September Ruby’ reach five feet at the end of the flower border.
Some gardeners like to give their asters a cut-back before July 4 to encourage bushier growth, but I like mine wild, tall, and leggy for the most part. I mainly grow them in a long border with other perennials so that the bottom leaves on the stems, which can yellow by fall, are hidden by other plants. They are easy to stake if they’re leaning in the wrong direction.
Asters were given one of their oldest English names, Michaelmas daisy, because they bloom around Sept. 29, St. Michael’s Day.
This time of year, you’ll see smaller dome-shaped asters for sale next to the greenhouse-grown chrysanthemums that are used for front door container displays. Many of these Aster novi-belgii hybrids have the name Yoder Brothers on the tag for the Ohio family nursery that bred them decades ago (now owned by Syngenta, a giant global agricultural conglomerate). I don’t buy many of them because of their small stature, around 18 inches high, though I would put them in a seasonal pot display. I’ve had the best luck buying my asters in the spring so that they can settle into the border without looking like out of place domes. Look for them at local nurseries or order them from sources such as Prairie Moon Nursery or Bluestone Perennials.
Calico aster ‘Lady in Black’ has dark purple foliage in summer and is covered with a cloud of white flowers in autumn.
My oldest asters are in their third season, so next spring I’ll divide them if the stems seem too crowded. I let my asters go to seed and have discovered several new plants shooting up in unexpected places. If you don’t want this to happen, deadhead the plants before the seeds ripen. I like getting the free plants, and the fact that they might interbreed and make a new color of aster is a plus in my mind.
This year, one of the writer’s New England asters grew to more than seven feet at the back of the border.
Usually, I like to keep track of the plant names in my garden, but with all the confusing name changes and the tendency for the plants to interbreed and create new crosses, I don’t bother about it too much. I’m content adding to my aster collection with whatever strikes my fancy, and I don’t get hung up on nomenclature. Like the dozens of pollinator varieties that cover my flowers this time of year, I’m happy this bold group of plants has decided that October, when most everything else is in decline, is the time to shine.
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