Asters are the perfect solution for a color-challenged fall garden.
They fill the gap created by the decline of summer-blooming annuals and perennials. They are also suitable companions to other fabulous fall-blooming annuals and perennials like goldenrod, pansies, mums, ornamental cabbage and sedum.
The flowers of asters are star-shaped with rayed petals surrounding a golden yellow disk. Most asters bloom in shades of purple, pink, lavender or white from early September through October. Many different species of butterflies and honey bees are attracted to their nectar.
Asters are available in a variety of heights so there is a cultivar perfect for every garden. Shorter types, like the wood asters, are ideal for the front of the border; taller varieties, like some of the New England asters, are best suited toward the back. Mid-sized asters in the 18- to 24-inch range belong somewhere in between.
Asters are also good candidates for container gardens helping turn summer-worn plantings into fresh fall displays.
Needing little special care, asters only ask that they are planted in full sun or light shade in moist, but well-drained soil. Give them their space when planting -- good air circulation will reduce the chance of fungal diseases like powdery mildew. Shorter varieties should be at least 18 inches apart; taller varieties up to 3 feet apart.
To keep taller types a little shorter and the foliage denser, prune them back twice beginning in early spring. Simply pinch stems back a few inches. Or you can shear the entire plant by half once later in spring. But no more pinching or shearing after early July -- the plants need time to set flower buds.
Divide asters every few years in spring to maintain overall plant vigor and form. Transplant the sections from the perimeter of the plants; discard the aged centers.
New England asters
Generally tall varieties reaching 2 to 4 feet tall, New England asters grow natively in open fields. They perform best in full sun. Alma Potschke boasts bright rosy-pink flowers on 3- to 4-foot stems. Partner it with Arkansas Amsonia and one of the new, shorter goldenrod varieties like Goldrush -- a beautiful late summer and fall display.
The ever-popular Purple Dome is a shorter variety barely reaching 2 feet, but it makes up for its lack of height with blazing purple flowers -- a vivid color easily mixed into the fall border with smaller ornamental grasses, sedum and coneflowers.
New York asters
Alert stops traffic with its rich violet-red flowers with bright yellow centers. This compact 12- to 15-inch tall aster is spectacular planted beside Fireworks goldenrod.
Celeste sports masses of dark lavender flowers on plants growing 18 to 24 inches tall; Peter III grows up to 18 inches tall and features lavender-blue blooms; and Puff shows off white flowers on slightly taller plants.
Descendants of New York asters, the Wood's series offers small types that easily fit in the front of the border or in container gardens. Their dark green foliage has better disease resistance than their predecessors, and there are cultivars available in pink, light blue and white. No taller than a foot, they are lovely planted with ornamental cabbage and pansies.
Wood asters, botanically known as Aster divaricatus and not to be confused with the Wood's series, are a great choice for shade gardeners. They grow about 2 feet tall and brighten up the late summer and fall border with tiny, white daisy-like flowers. Combine it with other shade lovers like coral bells and hostas.
Aster oblongifolius, a North American native, forms a mound of aromatic foliage and lavender-blue flowers appear in September and October.
Raydon's Favorite reaches 3 feet tall. Plant it near Dallas Blues switch grass. The color of the flowers complements the blue blades of the ornamental grass -- lovely. Edge this pair with lamb's ears -- now it's stunning!
My favorite is not a native, but I love Jindai -- a Tartarian aster originating in Mongolia. It has huge basal leaves and can grow up to 5 feet tall, although in my garden it stays closer to 3 feet. Its stiff stems never need staking and it colonizes by rhizomes. Not for a small space, it spreads to form a magnificent, weed-inhibiting stand of lavender blue flowers in late September and October. Jindai is a butterfly magnet.
Don't surrender your beds and borders to a dull, drab autumn. Plant perennial asters and celebrate the color in your fall landscape.
• Diana Stoll is a horticulturist and the garden center manager at The Planter's Palette, 28W571 Roosevelt Road, Winfield. Call (630) 293-1040, ext. 2, or visit planterspalette.com.