Asters fill the fall garden with flowers
If you are looking for perennials to fill the gap created by the decline of summer-blooming annuals and perennials in a sunny landscape, asters may be the perfect solution.
Asters can take the lead role in your border's fall performance, but are also happy to co-star with other fall-blooming perennials like goldenrod, Joe-Pye weed, sedum and ornamental grasses.
The flowers of asters sport golden yellow centers surrounded by rayed petals. Most asters bloom in shades of pink, lavender, purple or white beginning in early September and continuing through October. Asters are favored by many species of butterflies, bees and other pollinators.
Available in a range of heights, there is a cultivar perfect for almost every garden. Small asters are ideal for the front of the border; taller varieties are best planted toward the back. Mid-sized asters belong somewhere in between.
Asters are also good candidates for revving up summer-worn container gardens.
Asters need little special care, only asking to be planted in full sun or light shade in moist, but well-drained soil. Give them enough room to "breathe" when planting - good air circulation reduces the chance of powdery mildew. Shorter varieties should be planted at least 18 inches apart; taller varieties need 3 feet.
Taller types can be kept a bit shorter with denser foliage if their stems are pinched back a few inches twice beginning in early spring. Or cut back plants by half once later in spring. Stop pinching or pruning by the Fourth of July so plants have time to produce flower buds.
Divide asters every few years in spring to keep plants happy and healthy. Dig up the entire clump, discard the center, and transplant the outer sections.
Reaching up to 4 feet tall, New England asters 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 shorter goldenrod varieties like Crown of Rays in a beautiful late summer and fall display.
Purple Dome is one of the most popular types. It makes up for its lack of height - only growing about 2 feet tall - with blazing purple flowers. It dazzles in the fall border with smaller ornamental grasses, sedum and coneflowers.
New York asters are distinguished from their cousins by their smooth leaves. The rich, violet-red flowers with bright yellow centers of Alert stop folks in their tracks. This compact 12- to 15-inch-tall aster is spectacular planted beside Fireworks goldenrod.
Puff sports white flowers on plants growing 2 feet tall; Celeste shows off masses of dark lavender flowers on slightly smaller plants.
The Woods series of asters are descendants of New York asters. Their smaller stature - no taller than a foot - is right at home in the front of the border or in container gardens mixed with pansies and ornamental cabbage. There are varieties available with pink, light blue or white flowers, and the foliage offers better disease resistance than their predecessors.
A North American native, Aster oblongifolius, flaunts lavender-blue flowers over mounds of aromatic foliage in September and October. Raydon's Favorite grows to 3 feet tall. Plant it near Dallas Blues switch grass. The color of the flowers complements the blue blades of the ornamental grass. Add lamb's ears to the plant partnership - wow!
My favorite aster is Jindai. Originating in Mongolia, this Tartarian aster grows large basal leaves and stems up to 5 feet tall, although in my garden they stay closer to 3 feet. Its stiff stems never need staking and it colonizes by rhizomes into a magnificent, weed-inhibiting stand of lavender blue flowers in late September and October. The butterflies love Jindai as much as I do.
• Diana Stoll is a horticulturist, garden writer and the garden center manager at The Planter's Palette in Winfield. She blogs at gardenwithdiana.com.