Cheryl Wilson revels in fall-blooming asters in her Amherst garden

Last modified: Wednesday, November 21, 2012

Aster means star and in my opinion asters are the stars of fall — more than chrysanthemums. Perennial asters make the garden border sing in October. These American natives have been extensively hybridized and make splendid ornamental plants.

Asters come in many heights from dwarf to towering and a wide range of colors from pure white to shades of blues, purples and pinks of all hues. They were popular, especially in England, in the early 20th century, but fell out of favor due to problems with mildew and the lack of interest in any fall bloomer other than a mum.

In the wild, aster flowers can be variable, a characteristic that assists plant breeders in developing new cultivars. Asters weren’t much appreciated before the 1900s, when the British rediscovered our natives and started breeding new strains. They called them Michaelmas daisies because they tend to be at peak bloom around the religious festival of Michaelmas on Sept. 29. Some of the famous British hybrids are ‘Winston Churchill’ and ‘Coombe Fishacre’.

A number of new hybrids have come on the market in recent years to boost American interest in perennial asters. Of special note are ‘Purple Dome’ and ‘Wood’s Blue’. The latter was reportedly bred by an apple specialist in Oregon named Ed Wood who was intrigued by asters. After his death, fellow horticulturist Lynn Caton introduced his new plants, which also include purple and pink versions.

However, Wood isn’t the only American who recognized the importance of our native asters. Richard Lighty of the Mount Cuba Center for native plants in Delaware bred ‘Purple Dome’ and introduced ‘Bluebird’, a form of A. laevis or smooth aster. And the popular ‘Alma Potschke’ was bred at Cornell University in Ithaca, N.Y.

Sky-blue plants are always among my favorites and I have several asters in that lovely hue. ‘Wood’s Blue’ thrives in my front garden and contrasts nicely with Zinnia ‘Zahari Yellow’ as well as with white-flowered garlic chive that has just gone by. The aster, which is a dwarf at 12 to 18 inches, begins blooming in late August or early September and is still going strong weeks later. Soon a newly planted white chrysanthemum will complement the clear-blue flowers of the aster.

Across the walkway is my new favorite, ‘Little Carlow’. It is a larger-flowered hybrid of the delightful native A. cordifolius that has myriads of tiny pale blue flowers. ‘Little Carlow’ is a cross between A. cordifolius and another native, A. novi-belgii, otherwise known as the New York aster. That prolific bloomer lines my South Amherst neighborhood, Pomeroy Court, this year thanks to the blessed failure of the town to mow the verges. The New York aster with pale-blue 1-inch flowers, has just 15 to 25 ray flowers around a yellow disk in contrast to its close cousin, the New England aster or A. novae-angeliae, which has up to 50 ray flowers around its central disk. Both New York and New England asters can be found in meadows throughout the Pioneer Valley.

I discovered ‘Little Carlow’ two years ago on a visit to Sissinghurst Castle in England. At the time I didn’t realize it was related to A. cordifolius, a plant I had tried for years to cultivate. Ironically, after I finally purchased the tiny-flowered native about five years ago it has self-seeded all over my yard, much to my delight. But I do find now that I am rooting out some seedlings so they don’t overwhelm the rest of the garden.

Finding ‘Little Carlow’ was a bit of a challenge. No local nursery seemed to stock it so I went online to mail-order nurseries. Digging Dog Nursery in Albion, Calif., offered it so I ordered three plants. Two are thriving in their second year in my front garden but the third plant in the barn garden evidently was eaten by rabbits or overwhelmed by other plants.

There is nothing little about ‘Little Carlow’. Like A. cordifolius it grows 3 to 4 feet tall, but unlike the native, the hybrid has 1-inch clear-blue flowers. It looks great beside a yellow dahlia on one side and a potted red mandevilla on the other. Digging Dog describes it as “lush and chipper.”

Origin of garden plants

I become obsessed with wanting to know the origin of hybrid plants and the reason for their names. Fortunately the Internet helps my research. While I still don’t know the origin of its name — perhaps Carlow in Ireland? — I learned that ‘Little Carlow’ was bred in the 1930s by Margaret “Daisy” Emily Thorneley, who lived from 1875 to 1950 in Devizes in Wiltshire. Her plant received an Award of Garden Merit from the Royal Horticultural Society in 1993 and is very popular in England. Paul Picton of Old Court Nurseries in Herefordshire, an aster specialty nursery founded in 1906 by Ernest Ballard, wrote in an article for the Hardy Plant Society that ‘Little Carlow’ is “a wonderful plant combining the best characters from both parents: stout, long-lived clumps of graceful 120cm sprays of bright lavender-blue flowers over a long season.”

I found this information when researching Ernest Ballard, who named many of his introductions for women in his family, including ‘Patricia Ballard’ and ‘Marie Ballard’. He seemed to like bright-pink asters that aren’t in my garden palette.

Another blue-flowered aster that I have loved for years is called ‘Blue Lake’ I believe. I purchased it about 20 years ago from a now-defunct small nursery in Washington state and have tried to nurture it. This year, however, only a few stems emerged and the drought wasn’t to their liking. Next spring I must take special care or I will lose it altogether. ‘Blue Lake’ is a much shorter plant than the natives or ‘Little Carlow’, growing about 18 to 20 inches tall, but it shares that sky-blue color with my other favorites.

A final aster which I have loved for years is ‘Treasurer’, a hybrid of the native New England aster. Its foliage is much coarser than the others and it is a giant in the garden. This year I thought I had pinched it back in the spring and perhaps I did but it still is at least 5 feet tall. Unlike my other asters, ‘Treasurer’ has deep-purple flowers and attracts oodles of monarch butterflies as well as bumblebees and wasps. In fact, all the asters are nirvana for insects of many kinds.

I fell in love with asters way back in the late 1960s when I visited Dumbarton Oaks in Washington, D.C., in the fall. The long garden beds were filled with tall asters in bold colors — purple, deep blue, raspberry pink and even magenta along with soothing white.

On the north side of the house I have a shade garden, mostly ferns and spring ephemerals. But a real eye-catcher in October is Cimicifuga simplex, also called bugbane or cohosh, with tall spikes of white bottle-brush flowers that attract pollinators galore. Aster cordifolius has self-sown here and makes a lovely light blue froth under the Cimicifuga. Keeping watch over this garden is the Mexican pottery owl my late husband bought in Lake Placid, N.Y., more than a decade ago. A spray of the aster nods over the owl.

Asters combine well with many other fall-blooming plants. From Digging Dog Nursery I also purchased Anemone x hybrid ‘Andrea Atkinson’, which has white flowers in bloom right now. Alas, I planted it next to the now-extinct ‘Little Carlow’ in the barn garden, too far from ‘Treasurer’ to create a garden vignette. I wish I had planted snapdragons this year since their spikes would make a lovely picture with asters.

Asters generally require full sun although A. cordifolius and A. divaricatus, commonly known as the white wood aster, will take considerable shade. Fortunately for me, asters like clay soil and South Amherst is definitely clay!

They prefer slightly moist soil that is reasonably fertile. Pinching the taller varieties is recommended, especially if you don’t like to stake plants.

Asters probably should be planted in the spring but right now garden centers are featuring greenhouse-grown ones such as ‘Henry III’ and ‘Days Blue’ that are perfectly hardy. Leave their stems over the winter and cut them down to the ground in the spring. A mulch around the crowns may also help in the first year, especially with the fall-planted specimens.

Some asters do well as cut flowers but those related to New England aster — like ‘Treasurer’— close their blooms at night so aren’t good for an arrangement for a dinner party.

Give asters a chance in your garden. They go well with the popular ornamental grasses as well as with late-blooming annuals and perennials. And they certainly do make a garden sing in the fall.

Cheryl B. Wilson can be reached at


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