Ornamental grasses sway in the fall breeze
Close your eyes and picture a fall landscape. I'd bet the farm (if I had one) that the landscape in your imagination includes ornamental grasses. They are the backbone of the fall perennial border where their foliage offers shades of the season; their seed heads contribute texture and their stems add motion to the garden as they sway in autumn breezes.
Some of the best ornamental grasses are native to the Midwest. Once they are established, they need very little supplemental watering or maintenance. An annual haircut in early spring before new growth begins is all that is required.
Big bluestem, botanically named Andropogon gerardia, was once one of the main plants in the tallgrass prairie. It grows 4 to 6 feet tall and half as wide, and performs best when planted in full sun and well-drained soil. Its foliage is purplish blue-green in spring, green with reddish-purple tones in summer, and coppery red in fall. If big bluestem is coddled with moist, rich soil, their stems may become lax. Plants will be more upright if big bluestem's deep and extensive root system is provided drier, infertile soil.
Flowers, resembling a turkey foot, rise on stems a couple feet over the foliage in late summer. Big bluestem is beautiful planted in large groupings in prairies or meadows, on steep slopes where its roots will reduce soil erosion, and as a background plant in the perennial border.
Little bluestem, Schizachyrium scoparium and sometimes Andropogon scoparius in botanical circles, grows a bit smaller - 2 to 4 feet tall and up to 2 feet wide - and is an ideal choice for sunny landscapes with poor soils. Another of the dominant grasses in the tallgrass prairie, its blue-green foliage turns from orange to coppery red in fall. Purple-tinted, copper-colored flowers appear well above the foliage in summer followed by fluffy, white seed heads in fall.
Blue Heaven is a narrow, upright cultivar sporting nice burgundy-red fall color. Carousel is a compact cultivar, growing just over 2 feet tall. The foliage of The Blues is bluer than other varieties.
Gardeners with regular visits from deer will be glad to know both big and little bluestem are not on their preferred menu.
When you walk through a landscape and get a whiff of buttered popcorn, look for Sporobolus heterolepis, commonly called prairie dropseed. This fine-textured grass forms arching mounds 2 to 3 feet high and wide. Fragrant, airy, pale pink flowers bloom in summer; its foliage turns golden orange in fall.
Plant prairie dropseed in a sunny spot with well-drained soil. It is drought tolerant once established but may require supplemental watering during severe drought conditions.
Tara is a dwarf cultivar that grows more upright than the species but just a foot tall and wide. It is perfectly suited to the front of a perennial border.
Switch grass (Panicum virgatum) was another common grass in the tallgrass prairie. Its sturdy stems grow 5 to 6 feet tall. Chosen for its stature and adaptability, switch grass boasts a cloud of tiny flowers that turn to reddish seed heads at the top of the plant. Its blue-green foliage turns golden yellow in fall.
Although switch grass is adaptable, it prefers full sun and lean soil. Rich soil or too much shade may cause stems to flop. Utilize it as a screen for unsightly views or plant it as a background plant in the perennial border. Reseeding can be a problem in gardens without mulch.
Switch grasses offer a group of cultivars ranging in size from 3 to almost 7 feet tall. Heavy Metal grows just 4 feet tall and features blue-gray foliage. Northwind is an especially upright variety, standing straight as a 5-foot soldier. Ruby Ribbons flaunts vivid reddish-purple fall foliage.
• Diana Stoll is a horticulturist, garden writer and the garden center manager at The Planter's Palette in Winfield. She blogs at gardenwithdiana.com.