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Nature Notes
Native Ornamental Grasses for Pennsylvania by Ed Dix, Botanist, DCNR Bureau of Forestry Ornamental grasses are a regular feature in Pennsylvania gardens. Most display we find the same few species of Pampas grass (Cortaderia spp.), Miscanthus or Pennisetum. None of these are native to North America. For those of us gardening with native species, there are several grasses available that offer striking aesthetic values and support native biodiversity as well. For horticultural purposes, different characters group the varieties of grasses. By growth form, grasses are divided into clumpers and runners. The “bunch grasses” form distinct clumps with many stems but spread only slowly. Runners spread rapidly by extending long rhizomes or stolons. Sorting the species by the season of their most vigorous growth gives us “warm-season” species that grow during June, July and August versus “cool-season” grasses. Cool season species begin growing in late winter but go dormant in hot, dry weather. They often have another growth spurt when temperatures drop and rains increase in autumn. Our selection of native species begins with Big bluestem, (Andropogon gerardii). Big bluestem is sometimes called “Turkey foot” due to the shape of its inflorescence. It grows 5-7 feet high on riverbanks, roadsides and moist meadows throughout Pennsylvania. In the garden it adapts to a wide range of soil conditions but does poorly in shade. Big bluestem is a warm season, bunch grass with deep roots. The stems are rigid and remain standing through the winter, providing shelter for wildlife in mass plantings. Songbirds feed on the seeds. Big bluestem’s aesthetic appeal is in lush green or blue green foliage in summer and rich orange and copper red tones from fall through winter. Little bluestem, Schizachyrium scoparium, inhabits old fields, roadsides and open woods in central and southern counties of the Commonwealth. It grows best in soil pH between 5.5 and 6.5 and is extremely drought tolerant. Older books will refer to it as Andropogon scoparius, but botanists now sort it into the genus Schizachyrium because its flower heads differ in shape from the Andropogons. Clumps of Little bluestem have fine textured leaves standing 2-4 feet tall. A warm season grass, its form varies from rigidly erect to lax and arching. The blue green foliage makes an excellent backdrop for summer wildflowers in mixed plantings. In the fall, it glows with superb shades of orange-red. Indian grass, Sorghastrum nutans, and Big bluestem were the dominant species of the North American tall grass prairies. In Pennsylvania, Indian grass is found in moist or dry fields and roadsides in all but the northern-most counties. This warm-season clump forming grass grows to 4-6 feet in full sun. In August, Indian grass produces flower spikes in coppery red with bright yellow anther. It is the most striking floral display of all our native grasses. In fall, the dried inflorescence is chestnut brown above the orange tinted foliage and it remains attractive all winter either in the garden or as a dried arrangement. As with the other selections, it requires little maintenance other than to be trimmed back in late winter. Another warm-season prairie grass now found in the ornamental trade is Switch grass, Panicum virgatum. There are many horticultural selections that vary in size from 4 to 8 feet. Summer foliage colors range from deep green to gray-blue. In the fall they offer shades of golden yellow, some with streaks of wine-red. Switch grass sends up airy, reddish panicles in August and September. All varieties form clumps, but some also spread by short rhizomes. Agricultural cultivars are planted for erosion control, wildlife food and shelter and even for pasture hay. Among cool-season native grasses, the most readily available is Bottlebrush grass, Elymus hystrix (also listed as Hystrix patula). In the wild, Bottlebrush is adapted to moist, alluvial woods and so, is shade tolerant. It reaches 2 to 5 feet in height. The decorative inflorescence that gives it its common name appears in June and remains attractive through autumn. Other species of Elymus are sold as conservation grasses for soil stabilization and wildlife habitat. Riverbank wild-rye E. riparius, and Virginia wild-rye E. virginicus, are native bunchgrasses of moist woods, meadows and stream banks. However, they have less to offer as ornamentals. A popular use of native grasses is as a background for bright wildflowers in naturalized meadow and prairie gardens. If you start from seed, be patient as these species grow down in the first season, establishing good root systems. Foliage development improves in the second and third years. From then on, they will be a low maintenance source of delightful textures and colors and a sanctuary for songbirds, cottontails and other wild neighbors. Sources The Color Encyclopedia of Ornamental Grasses. Rick Darke Timber Press; 1999. Pennsylvania Wildlife No. 12 —Warm-Season Grasses and Wildlife. Penn State Cooperative Extension. “Landscaping with Native Plants in Pennsylvania” Pa. Department of Conservation and Natural Resources.
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