When most other perennials stop blooming, asters are just getting started. These hardy perennials are the backbone of the late show, says Gary Ratway, co-owner of Digging Dog Nursery in Albion, California.

"Most of the year asters are just a promise, just a nice clump of green foliage," he says. "But then, finally, late in the season, when you're craving another jolt of color, out they come with these great clouds of flowers."

Those clouds, appropriately enough, are often blue. But asters also come in a full range of reds and pinks, plus white.

And asters attract winged guests: Monarchs and other butterflies love the flowers. Bees like them too.

Autumn is the time to go nursery shopping for asters in bloom. Where winters are frost-free, you can plant any time as long as the soil isn't soggy. In cold-winter climates, get plants into the ground no later than mid-October or wait until next spring.

BEST ASTERS FOR THE WEST

A. cordifolius. Violet blue flower clusters resembling baby's breath are borne on stems 4 to 6 feet tall. Great in bouquets. Sunset climate zones 1-10, 14-21 from the Western Garden Book.

A. x frikartii. One of the earliest-flowering asters, it's also one of the latest bloomers. The variety 'Mönch' bears 2 1/2-inch-wide lavender blue flowers on a 2- to 3-foot-tall plant; 'Jungfrau' and 'Wonder of Staffa' are similar. Plant looks best when stems are staked or grown in a hoop. Zones 2b-24.

A. novae-angliae hybrids. Very upright (3 to 5 feet tall), this stout-stemmed aster has 2-inch-wide flowers and hairy leaves. 'Alma Pötschke' (salmon pink), 'Purple Dome', and 'September Ruby' are popular varieties. Zones 1-24.

A. novi-belgii hybrids. Plant form is similar to A. novae-angliae, but the leaves are smooth. There are scores of named varieties ranging from dwarf kinds like 'Bonny Blue' (violet flowers; 10 to 12 inches high) to tall ones like 'Winston S. Churchill' (raspberry red; to 3 feet) and 'Climax' (true blue; to 6 feet). Zones 1-24.

A. pringlei 'Monte Cassino' (also sold as A. ericoides 'Monte Cassino'). Sprays of small white daisies are borne on branching 3- to 5-foot-tall plants. Excellent cut flower. Zones 1-24.

Sources for Asters

A. x frikartii and short- and medium-height A. novae-angliae and A. novi-belgii hybrids are available at many nurseries. Taller asters are harder to find; shop at specialty nurseries or try one of the following mail-order sources.

Bluestone Perennials: (800) 852-5243 or www.bluestoneperennials.com.

Canyon Creek Nursery: (530) 533-2166 or www.canyoncreeknursery.com.

Digging Dog Nursery: (707) 937-1130 or www.diggingdog.com.

Forestfarm: (541) 846-7269or