Aster season is just beginning. These bright, starry flowers ("aster" comes from the Greek word for "star") positively shine in the early fall garden. They may start in August--some even as early as July--and extend the blooming season by as much as six weeks. Although gardeners in the coldest zones risk losing some flowers to early frosts, asters are tough, reliable perennials hardy just about anywhere in Canada. Early-blooming types suitable for short-season areas are also available.
As if that were not enough, their multitudes of flowers in shades of blue, pink, red or white are renowned for attracting butterflies. Asters also make superb, long-lasting cut flowers. And although their nickname, Michaelmas daisies, makes them sound quaintly English, the ancestors of almost all cultivated asters are native to Canada from Newfoundland to B.C., and to the northern half of the U.S., encompassing Zones 2 to 5. Aster species can be found in almost any Canadian habitat: prairies, mountain slopes, seashores, damp meadows, woodland edges, scrubland and even along roadways. These plants are survivors.
Very early in the 1700s, seeds of two species of North American asters were taken to England. There, their hybridized progeny quickly became popular both in formal borders and in grow-what-may cottage gardens. One was Aster novae-angliae (literally "New England aster"), a tall (120 centimetres) species, hardy to Zone 2, native from Quebec to Alberta and as far south as North Carolina to Colorado. The other was Aster novi-belgii ("New Belgium," an early name for New York), a slightly shorter, Zone 3 species native from Newfoundland, Quebec and Nova Scotia south to Georgia. Because of their unusually late blooming time--around Michaelmas, an English church holiday celebrated every September 29--the new daisy-petalled, yellow-centred hybrids became known as Michaelmas daisies. The name stuck, and now refers to any cultivated aster that blooms in the fall.
Whatever you call them, these stars of the fall garden now come in tall, medium and dwarf forms; with single, double or semi-double flowers; in upright, rounded or mounding shapes; and in tones of pink, white, purple, violet, rose-red, magenta, mauve and every conceivable shade of blue. Best of all, in modern hybrids the two drawbacks of the earliest hybrids--ranginess and a susceptibility to powdery mildew--have been all but eradicated.
Although a few types are tolerant of drier soils, most asters (including modern hybrids) definitely need rich, moisture-retentive soil that does not dry out in late summer or early fall. Full sun and good air circulation are also important; asters evolved in wide-open, exposed sites and are not happy in shady or crowded conditions.