By Sue Rideout
UCCE Master Gardener

Colorful fall gardens often include the September birth flower, aster, with its happy rayed flower gathered around a cheery yellow disc. More commonly grown in the Eastern U.S., it can add autumn splendor to our gardens.

The Aster genus belongs to the sunflower or daisy family which comprises more than 23,000 species including the familiar sunflower, coneflower, chrysanthemum, dahlia, cosmos, daisy, zinnia, marigold and many others. The aster genus itself includes some 600 species.

The cultivation of asters is relatively simple. They prefer an average to fertile well-drained soil and regular water, in full to part sun. Photo courtesy of Master Gardeners, University of Wisconsin Extension.

The cultivation of asters is relatively simple. They prefer an average to fertile well-drained soil and regular water, in full to part sun. Photo courtesy of Master Gardeners, University of Wisconsin Extension.

A single aster flower head is really composed of over 100 tiny orange-red tubular flowers surrounded by petals in shades of purple, blue, white, red, or pink. The tubular flowers make up the center disk of the head and the petals are ray flowers. The aster derives its name from the Greek word for star because of its shape.

Most asters are perennials but some are annuals or biennials. Listed below are some of the more common perennials. 

New England Aster (Aster novae-anglise): Despite its name this aster is native from Vermont to Alabama and west to the Dakotas, Wyoming and New Mexico. The strong stemmed plants grow 3 to 5 feet high with two inch blossoms in shades of blue, purple, pink, and white. ‘Purple Dome’ is a compact variety sporting brilliant deep purple clusters of blooms on mounding 1½ foot plants.

New York Aster (A. novi-belgii): These asters, also known as Michaelmas daisies, grow to 4 feet high and 3 feet wide with two inch blossoms in shades of bright blue-violet in their standard form. Many varieties have been developed ranging from 1 to 4 feet with flowers in shades of white, blue, purple and pink.

Hybrid aster (A. x frikartii): This hybrid is considered by many to be one of the most useful and widely adapted perennials. Native to the Himalayas and developed by a Swiss botanist, Carl Frikart, this flower is well-adapted to United States gardens—a real globe trotter! Soft lavender-blue flowers are borne on open growth plants about 30 inches high. Plants are somewhat floppy and need to be staked for a formal garden appearance. ‘Monch’ and ‘Wonder of Staffa’ are good varieties which will bloom from summer through fall, almost year around in mild winter areas if dead blooms are plucked.

North American native Aster (A. lateriflorus): This aster requires somewhat less water than most others. It grows 2 to 3 feet high with extensive branching and profuse small pinkish flowers. Its tiny leaves turn coppery red in the fall. ‘Lady in Black’ has purplish black foliage and clouds of red-centered white blossoms. 

The China Aster (Callistephus chinensis) is an annual plant, which makes an excellent cut flower favored by florists. Planted in spring, bloom comes in summer. There are many different flower foms (just as there are for chrysanthemums) including pompon, anemone and ostrich feather, quilled, ribbonlike and curled. The problem is that it is much more prone to a couple of diseases like aster yellows (a virus) and a soil borne wilt (caused by a fungus) so it cannot be planted in the same location in successive years. Regardless it is still a very commonly grown bedding plant. 

Cultivation of asters is relatively simple. They prefer an average to fertile well-drained soil and regular water, in full to part sun. Asters can be grown from seed but perennial asters are usually started from nursery transplants or by division. If your neighbor has an aster you like, ask for a clump when it is time to divide. Local nurseries sell plants but mostly in the spring, although early fall is a great time to plant. Mail order nurseries also stock a variety of asters.

Aster care includes regular watering, but these sturdy flowers will forgive an occasional miss if you are on vacation or (like me) just absent-minded! For more compact growth and a bushier look, asters can be pinched back by about a third in early to mid-June, but never later than mid-July. Deadheading spent flowers prolongs the bloom period. After blossoming is over for the year, prune the plants back.

Asters are quite resistant to insects and diseases. Powdery mildew can be a problem to the foliage. This can be controlled by dividing the plants every 2 to 3 years, giving the plants more air flow. Just dig up a clump and divide into 3 or 4 smaller clumps, discarding the center if it is getting woody. Replant the small clumps and water well until they are established. Division has the double advantage of making the plants healthier and providing more asters for you or a friend.

Asters are a magnet for pollinating insects and butterflies in a habitat garden. So for fall color and great cut flowers, try some asters in your garden. Chrysanthemums, also a fall bloomer, make great companion flowers.

The UCCE Master Gardeners will be available to answer your gardening questions in Hanford at the Greenfield Garden Workshops, 2 p.m., on Sept. 30. 

To contact the Tulare/Kings Master Gardeners, call 559-684-3325, e-mail [email protected] or write to 4437 S. Laspina St., Ste. B, Tulare, CA 93247.

This column is not a news article but the opinion of the writer and does not reflect the views of The Foothills Sun-Gazette newspaper.

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