There are plenty to choose from. Your garden’s sun, shade and soil will determine which one is best.
THE DAYS MIGHT still be warm and sunny, but they’re undeniably growing shorter as we slide toward the fall equinox. While dahlias and coneflowers continue flowering, asters and tall sedums like ‘Autumn Joy’ come into their own. As do ornamental grasses, most of which bloom shortly before or after autumn’s start.
But the flowers aren’t the point of these late-season stalwarts, except to the birds, who adore their seed heads. We plant grasses to add motion to the garden — for they ripple with every passing breath of wind — as well as height, color and unique textures.
If you’ve ever tried to drive a sharp spade into a miscanthus when it’s time to divide up a big old clump, you know that all ornamental grasses aren’t created equal. Some of the most beautiful, like purple fountain grass, don’t last the winter in our climate. Others, like fluffy feather grass (Nassella tenuissima) seed about relentlessly.
So which are the best grasses for autumn in our climate? It depends on the conditions your garden offers up in terms of sun, shade and soil. Really, there are so many choices that it comes down to aesthetics. Big and bold? Slender and shimmery? To grow in a pot; mixed into a border with perennials; or planted as a wide, sweeping river of textural color?
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The light and airy switch grasses, prairie plants all, bring a kinetic quality to the garden. Panicum virgatum ‘Blood Brothers’ has a graceful, colorful presence in the garden year-round. Its foliage comes on as a combination of red and green that lasts through the summer, then turns a brighter red in autumn. In winter, it fades to a lovely clump of tawny auburn that persists until it’s time to cut it back in early spring. P. virgatum ‘Cheyenne Sky’ is more petite, growing to about 3 feet tall, with blue-green leaves that turn wine-red in summer, topped by purple flower panicles. Both grasses are drought-tolerant and deer-resistant.
You rarely grow a grass for its flowers, but the flat, dangling, almost reptilian blooms on Northern sea oats (Chasmanthium latifolium) are curiously compelling, and dramatic in bouquets. The foliage is bamboo-like, and turns coppery-colored in autumn. And it’s one of the few grasses that prefers at least partial shade and moist soil.
In contrast, black-flowering fountain grass (Pennisetum alopecuroides ‘Moudry’) is all about texture. The foliage is glossy, topped by dark foxtail-like flowers that look nearly black in contrast to the plant’s yellow and orange autumn foliage. Picture a ribbon of 3-feet-tall clumps of ‘Moudry’ running through a perennial bed planted in lavender asters and black-eyed Susan.
Libertia ixioides ‘Taupo Blaze’ isn’t really a grass, but it reads like one in the garden. This short, colorful New Zealand iris is my current favorite plant. Its spiky, swordlike blades of foliage are a unique blend of deep green, yellow and orange, morphing to scarlet in autumn. It grows slowly to 2 feet tall, lives happily in containers, and has white starlike flowers in spring and showy burnt-red berries in autumn. Kind of a grass with benefits.
There are so many fascinating grasses to choose from; these are just a few I especially love. Each is dependably hardy, not much trouble to take care of, and looks its best late into the season. If you leave the spent stalks standing, they’ll attract enough birds to liven up the garden well into winter.