A Fall Bounty of Native Asters
By Allan M. Armitage

Perhaps it is the familiarity with our roadside asters, a number of which are indisputably weedy, that has held back the popularity of the named cultivars in this country. However, horticultural improvements have greatly enhanced our native asters’ garden value, and they are becoming much more appreciated as the movement to more natural landscapes gains momentum.

Although many useful species are native to the United States, credit for much of the breeding work must be given to English and German nurserymen. Selections were made starting in the late 19th century. and new ones continue to be introduced every year.

The flowers of most aster species are white or in the blue to purple range (although many pink cultivars have been selected). The leaves are alternate and the daisylike flowers are borne either singly on the flower stem or in multiple-flowered panicles or corymbs. Most spread by rhizomes—underground stems—and a few can become overly aggressive.

Many asters are fall flowering, others reach peak bloom in the summer and then may rebloom in the fall if spent blossoms are removed immediately.


The Big Two

Most people who grow American native asters have cultivars of either New England or New York asters, which have been the focus of most of the breeding work thus far. Times are changing, but these are still at the head of the class.

New England Aster

Aster novae-angliae, USDA Hardiness Zones 4–8, AHS Heat Zones 8–1. Now classified Symphyotrichum novae-angliae.)

This common wildflower found widely in the eastern United States is one of the largest and prettiest in the genus but is seldom seen in cultivation, having been superseded by bigger, but not always better, cultivars. The entire, four- to five-inch-long leaves are numerous and very hairy. This species and a few others similar to it may be separated from many other asters by looking at the base of the leaves. The two basal lobes of the leaves clasp the stem, poking out on either side. The flowers are one-and-a-half to two inches across and consist of 40 to 50 ray flowers surrounding a yellow center. They are excellent for cutting, but beware of the hairy stems, which can cause a serious skin rash on hands and arms of susceptible individuals.

Cultivars

Dozens of cultivars have been offered. Here are a few of my favorites that have stood the test of time.

Alma Pötschke (‘Andenken an Alma Pötschke’) is an excellent three- to four-foot-tall selection with bright rose flowers that are one to two inches across and have slightly curled petals. Although less prone to topple than other selections, it still requires support.

‘Harrington’s Pink’, developed by Millard Harrington of Williamsburg, Iowa, is one of the most popular asters today. This three- to five-foot tall plant bears large salmon pink flowers from September through October.

‘Purple Dome’ is a terrific introduction from the Mt. Cuba Center in Greenville, Delaware. Late flowering on 18- to 24-inch stems, plants maintain a compact, mounded habit supporting hundreds of deep blue flowers. In regions with high summer humidity, leaf and stem disease can be a major problem. Regardless, this is a great aster for the front of the sunny garden.

‘September Ruby’ (‘Septemberrubin’) has inch-wide, deep ruby-red flowers on three- to five-foot stems. Although classified as a late bloomer, flowering begins in late May here in northern Georgia and continues through late June. If the flowers are deadheaded, it blooms again in September. Flowering is three to four weeks later in the Northeast, but seldom do flowers peak in the fall.

New York Aster

(A. novi-belgii, Zones 4–8, 8–1. S. novi-belgii var. novi-belgii.)
There are literally hundreds of cultivars of this wonderful roadside weed, which is also commonly known as Michaelmas daisy because it blooms around September 29, St. Michael’s Day, in the British Isles. The specific epithet, novi-belgii, arose because the state of New York was once known as New Belgium. The history of breeding of Michaelmas daisies is a who’s-who of horticulture including the Honorary Vickary Gibbs, Ernest Ballard, A.H. Harrison, and Alan Bloom.

The leaves of New York asters clasp the stem much like those of New England asters, but the smooth or nearly glabrous leaves differentiate the two species. Also, the flowers normally have only 15 to 25 ray flowers. They are not as good for cut flowers as the New England asters, but they provide excellent color in the late summer and fall garden.

Dwarf cultivars are excellent for containers and the front of the garden, and, best of all, require no staking. However, many medium-size cultivars (under four feet tall) do need staking, especially those with large flowers. I hesitate to recommend any cultivars over four feet tall. They are too tall for most gardens, require extensive support, and can become invasive.

Dwarf Cultivars

‘Lady in Blue’ is about a foot tall with blue flowers in the fall.
‘Little Pink Beauty’ is one of my favorite asters. This plant is covered with semi-double pink blossoms in the fall.

‘Professor Anton Kippenberg’ is nine to 12 inches tall and carries lavender-blue semi-double flowers.

Sapphire (‘Kiestrbl’) was introduced to North American gardeners in 2005. Plants are covered with lavender ray flowers surrounding yellow centers on a 12- to 16-inch-tall mounding plant.

‘Wood’s Dwarfs’ are wonderful eight- to 12-inch-tall plants with purple-blue (‘Wood’s Purple’), pink (‘Wood’s Pink’), and light blue (‘Wood’s Light Blue’) flowers. In Georgia, they begin flowering around mid-September and persist for four to six weeks.

Medium-size Cultivars

‘Ernest Ballard’ has reddish-pink semi-double flowers up to three inches wide.‘Priory Blush’ grows at least four feet tall with double white flowers tinged with a little pink. It’s very attractive but needs some judicious early summer pruning.‘Winston Churchill’ bears handsome red daisylike flowers on two- to three-foot stems. They were fantastic in cut flower trials at the University of Georgia.

Lesser-Known but Deserving Asters

The following asters don’t get nearly as much attention as they should.

Climbing Aster

(A. carolinianus, Zones 6–9, 8–1 syn. Ampleaster carolinianus.)
If you live in a mild climate, you might want to give this aster, native to the southeastern United States, a try. Its common name is a bit deceptive because the plants don’t climb by themselves, but consist of lanky, arching stems up to 12 feet that produce dozens of one- to two-inch-wide pink to purple flowers with yellow centers along their lengths.
This is a rollicking shrub that takes up a lot of space, but if you train it on a fence or run it through a shrub, it is really impressive. It’s easy to grow in full sun but tolerates part shade.…


Photo credits: ‘Winston Churchill’ by Allan M. Armitage; Aster carolinianus courtesy of Plant Delights Nursery.
 

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