The Best Asters to Plant in a Garden

New England Asters

• New England asters (Aster novae-angliae or Symphyotrichum novae-angliae) are tough native perennials, hardy in USDA zones 5 through 8. Descended from meadow-dwelling plants, they are generally 3 to 6 feet tall with somewhat hairy leaves. Mature specimens are covered with scores of daisylike flowers. Among the best New England aster varieties is "Harrington's Pink," a tall variety with rosy pink flowers that scored a four-star (good) rating in the Chicago Botanic Garden's comprehensive six-year aster trial. "Honeysong Pink," with deeper pink flowers, received the same high score.

New York Asters

• New York asters (Aster novi-belgii or Symphyotrichum novi-belgii) are another group of native perennial asters that bloom reliably, increase year after year and are generally hardy in USDA zones 4 through 8. "Blue Lagoon," a dwarf variety, tops out around 18 inches tall and features blue or blue-purple flowers. A vigorous grower, it was chosen for inclusion in the Missouri Botanical Garden's plant collection. "Fellowship" won the Royal Horticultural Society's Award of Garden Merit in 2004. It grows up to 4 feet tall and bears large, double, pink flowers.

Award-Winning Asters

• A hybrid aster, "Monch" (Aster x frikartii "Monch"), was the winner of the AGM in 1993. Hardy in USDA zones 5 through 8, "Monch" grows about 30 inches tall and produces large quantities of medium blue or blue-purple flowers with yellow centers. Another AGM winner, "Little Carlow" (Aster x cordifolia "Little Carlow"), stands even taller, up to 48 inches high, and has a wider hardiness range of USDA zones 4 through 9. Like "Monch," "Little Carlow" bears blue-purple flowers.

Considerations

• Asters require a sunny exposure and are not fussy about soil. Many of the best varieties, like "Harrington's Pink," have a strong tendency to self-seed, which can be either a blessing or a curse for gardeners. To discourage self-seeding, remove spent flower heads promptly when they begin to fade and watch for stray seedlings in the spring. Many asters have a susceptibility to powdery mildew, a fungal disease
  that is a particular problem in humid weather. Maintaining proper planting distance to promote good air circulation and favoring drip irrigation instead of overhead watering help combat powdery mildew.