Asters are stars of the late summer and early fall garden.
Getrude Jekyll, English grand dame of perennial garden design, loved them so much that she devoted an entire border to asters (whose name means 'star' in Greek). Often called Michaelmas daisies since most varieties are in bloom during the feast of St. Michael and All Angels on Sept. 29, asters are wonderful bridges between dying summer perennials and autumn's resurgent bloom. Most start blooming in late summer.
"Asters give you a boost of color when other things have petered out," says Bob Hill, horticulturist at Park Seed Co. in Greenwood, S.C.
For example, a couple of 'Purple Dome' asters, stuffed into the slot where the now ratty-looking lamb's ears (Stachys) once thrived adds a showy new focal point to an otherwise scruffy corner. Additionally, their colors -- heavy on the blues and purples -- are a wonderful foil for the bronzes, reds, and golds of late-season plants.
"Asters and mums and grasses all go beautifully together," says Meg Sorrell, manager at Niche Gardens in Chapel Hill, N.C.
Fresh as a daisy
Asters belong to the Asteraceae family, which includes zinnias, dahlias, mums, and other daisy-faced bloomers like sunflowers. They range from 6-inch dwarfs like Aster alpinus to 7-foot giants like A. tataricus. There is even a climbing aster, A. carolinianus.
"We have one on our mailbox post," says Sorrell. "It has pretty grayish green leaves and rosy pink flowers that turn lilac as they age."
Like A. carolinianus, more than half of the 400 or so aster species are native to North America, including 4-foot tall New York asters (A. novi-belgii) and New England asters (A. novae-angliae), which wave violet-purple daisy-like flowers with yellow centers on 5-foot stems. The two wildflowers, which still adorn roadsides and edge sunny farm fields, have been favorites of European hybridizers who have used them to produce a host of new aster cultivars over the past century. Two of the newest New York hybrids to hit American markets are 'Sailor Boy Blue' and 'Crimson Brocade.'
"The 'Crimson Brocade' is a much darker red than any before it, and the 'Sailor Boy Blue' is a very dark blue," says Wanda Sorrells, senior horticulturist at Wayside Gardens in Hodges, S.C.
Though the perennial asters are generally hardy from zones 4-8, there are also annual asters that bite the dust at the first frost. But while the annual varieties require reseeding every year (they also reseed themselves, though rarely aggressively), they boast some really striking blooms. For example, 'Lilliput Blue Moon,' a 2002 introduction, is a 2-foot-tall mound covered in royal purple cushion-like blooms fringed in lavender, and 'Seastar' has lavender, white, pink, and rose flowers that look like undulating sea anemones.
The newest addition to the roster of annual asters is 'Starlight Mix,' which produces a 10-inch tall mound of large (3-4 inches) flowers in a range of bright blues, sky blue, scarlet and rose from mid-August to frost.
Yet while newer strains always command attention, some of the older varieties are still favorites. One of Meg Sorrell's all-time top picks is an older variety, Fanny's Aster (Aster oblongifolius).
"It has so many rich purple flowers and blooms pretty late -- October into November," she says. "It's just a beautiful plant and is very robust."
Aster x frikartii 'Monch,' which dates from a 1920 cross by Swiss nurseryman Carl Frikart, is the parent of a host of hybrids, yet is still very popular in its own right. With a beautiful lavender-blue daisy-face and golden center, it is also, with its daughter, 'Wonder of Staffa,' the longest-blooming aster around, usually producing flowers from August through October.
Caring for asters
"There isn't much that bothers asters," says Sorrells. "They don't have insect and disease problems, and once established, they can withstand drought well, but they have to have good drainage."
"Usually you don't lose asters in the summer," adds Hill, "but if the winter's been too wet, it can make the roots rot."
Some asters are prone to mildew in summer, though there are also mildew-resistant varieties like A. 'Nesthakchen' a compact, bright pinkish red mound about 18 inches high. Most asters like full sun, though some will take dappled shade.
" 'Rose Serenade,' with little rose-pink daisies, prefers a little shade rather than the full blasting sun," says Sorrell. "So do the wood asters. Aster cordifolius is an old-fashioned single blue wood aster that grows in light shade and Aster divaricatus is the white wood aster."
Pinching perennial asters back until mid-July (as with mums) will encourage branching and therefore more blooms on a more compact plant.
For all asters, deadhead periodically -- about once a week -- to prolong blooming. Deer rarely bother them.
Geo. W. Park Seed Co.
1 Parkton Ave.
Greenwood, SC 29647-0001
1111 Dawson Road
Chapel Hill, NC 27516
7530 NE 288th St.
Kingston, WA 98346
1 Garden Lane
Hodges, SC 29695-0001