Yet with a little shopping around, gardeners can add splashes of pinks, blues, whites and purples to their garden's autumn palette merely by selecting a different fall blooming perennial -- the aster.
The greater the assortment of asters, the more colorful the garden becomes. And with dozens of varieties available, this hardy perennial offers a delightful alternative from the traditional mums in the fall garden.
Small, colorful blooms
Though not planted as commonly as the mum, asters are becoming more popular.
Asters bear daisylike flowerheads with different-colored centers, often yellow. The arrangement of flower petals may be sparse, thin and long, like Aster thomsonii Nanus, giving the plant a spiky look. Or they may be thick, full and short, like Aster novi-belgii Apple Blossom, producing a flower with more of a pompom look.
But don't expect giant flowers. Typically, aster blooms are on the small side, ranging from 1 inches to 2 inches across.
Aster flowers sit atop stems that are usually tall and erect, though a few have spreading stems. The particularly tall varieties -- those reaching nearly 3 feet -- need staking to keep stems upright. The plant's foliage may be long and lance-shaped or broad and heart-shaped.
Both fall bloomers -- mums and asters -- have much in common. For one, the stems of both can be trimmed back in late spring or early summer to encourage bushiness and abundant flower production. Also, like mums, some aster varieties may need dividing every two or three years to promote plant hardiness and vigor.
Finally, though asters and mums are described as hardy for this zone, they sometimes fail to survive especially cold winters. Ample compost during planting and mulch for protection with the onset of winter may increase the likelihood of survival.
No matter the garden site, you are likely to find an aster to plant in it. Plant asters in wildflower gardens, in rock gardens, along a stream or pond, or in drifts in a mixed flower bed. Companion plants include goldenrod, Joe Pye Weed, ornamental grasses and white coneflower.
Cultivation is relatively simple and falls into three categories. One group of asters loves sunny sites with well-drained, moderately fertile soil. Another group prefers sun or partial shade with moist, fertile soil. The third group likes partial shade and moist, fertile soil.
Unfortunately, gardeners have found that pests and diseases sometimes plague asters. They may be prone to Verticillium wilt, gray mold, powdery mildew, rusts and fungal leaf spots. Aphids, slugs, snails and nematodes also have a taste for asters. To minimize pest and disease problems, follow sound horticultural practices.
Asters can be propagated with seed sown in containers or through plant division. To divide asters, lift the plant from the ground, rinse away soil to reveal its fibrous root system and separate runners. Replant only healthy asters, which will quickly establish new plants.
Not all asters are perennial. Like their cousins, annual asters provide a variety of bloom colors in late summer and early fall. Their flower heads may reach as large as 5 inches across and their height ranges from miniature 6-inch varieties to those that are 3 feet tall.
Unlike other annuals that tend to bloom all season, annual asters are in flower only about one month and do not rebloom when cut back. Of course, bloom time can be extended with staggered planting. Cut flowers are long-lived and air-dry well for preserving.
No matter the type of aster you plan to grow in your garden and in spite of the extra care that may be required, you will be rewarded with an attractive plant and sure-fire fall blooms. And, as a bonus, butterflies will flutter around the garden to visit the asters.
-- Carol Boncella is education coordinator at Lawrence Memorial Hospital and garden writer for the Journal-World.