Overview of Switchgrass

Switchgrass, Panicum virgatum, is one of many native prairie grasses that have been used as ornamental grasses. Switchgrass – also called tall panic grass, tall prairiegrass, wild redtop, and thatchgrass – is one of the main species of grasses of the North American tallgrass prairie, ranging from southern Canada (south of latitude 55° N) to Mexico over most of the United States east of the Rocky Mountains. It can be found in remnant prairies, in pastures, along roadsides in many areas, and even in brackish marshes. In the garden this species can provide nearly year-round interest, as the plants remain upright throughout the winter. It is also employed for soil conservation (to prevent erosion) and as forage or hay for cattle (but not other livestock), and its potential use as a biofuel has been explored by researchers. It is hardy in zones 3a-9b.

This long-lived perennial grass typically grows 2½-5 feet tall, slowly spreading by short rhizomes in all directions. It is a warm season grass, so it does not start growing until late spring. The species is quite variable in its vigor, height, cold tolerance, and sensitivity to moisture stress. Some types have a bunching habit, while others tend to be more sod-forming. All types are deeply rooted, growing a few to several feet deep in the soil.

The plants – especially ornamental cultivars – tend to have a dense, columnar form, with stiff round stems. Although rain or snow can bend the stems to the ground, many cultivars quickly bounce back up once the weight is gone; some of the taller varieties are more susceptible to flopping. The narrow leaves have a prominent midrib and a white patch of hairs where the leaf attaches to the stem. The medium green foliage may be tinged with red and turns various shades of yellow in the fall, bleaching out to beige over the winter.

Switchgrass blooms in mid-summer. The airy, pink-tinged flower spikes rise only about a foot or two above the foliage. The inconspicuous flowers with burgundy anthers and stigmas dangle from the well-branched panicles. The flower spikes can be used in fresh or dried arrangements. Teardrop-shaped seeds about 1/8 inch long develop from single-flowered spikelets. Ripe seeds may be pink or dull purple at first but turn a golden brown in autumn. The seed plumes persist well into winter, with the seeds eaten by songbirds and upland gamebirds. Self-sowing is usually minimal but can be prolific under ideal conditions.  Seedlings are frequently very different from the parents.

Landscape Use of Switchgrass

Use switchgrass massed or in groups at the back of perennial borders, in mixed plantings or in prairies and native gardens. This native grass mixes well with late blooming asters, sedums, Echinops ritro, roses, smokebush (Cotinus sp.) and garden phlox, as well as native prairie plants such as purple coneflower, rudbeckias, sunflowers, bee balm (Monarda spp.), and Liatris. In prairies it commonly grows with big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium) and Indiangrass (Sorghastrum nutans).

Switchgrass can be used as a focal point or as a vertical element in contrast to rounded or spreading plants in perennial gardens. Try combining it with cardoon (Cynaria cardunculus) for a color echo and great contrast in texture and form in a mixed border. It can also be used as a seasonal screen or near water or bog gardens. Try using small divisions as a vertical element in containers with a variety of annuals or tender perennials such as Plectranthus or coleus.

General Care of Switchgrass

Switchgrass grows best in full sun and moist soil but adapts to a wide range of soils and weather conditions. It will tolerate partial shade, although it may flop in too much shade. Once established, it is drought tolerant and grows well in high temperatures. In fertile soils the plants may flop and require staking. The clumps can be left standing through the winter and cut back to a few inches from the ground in early spring before growth resumes. This species has almost no insect or disease problems and rarely needs fertilizer. They do best when divided every three years.

Propagating Switchgrass

The species can be grown from seed, but cultivars must be propagated by division, preferably in spring just as the plants begin growing or until they reach about a foot high. The plants need warm soil to grow, so very early spring and fall planting is not recommended. For larger plantings in prairie restorations or meadows, plant the seed after the soil is warmed in spring. Seed needs no special treatment to germinate, and typically sprouts after 2-3 weeks in warm conditions. It usually takes about three years for the plants to mature, during which time weeds must be managed for best results.

Cultivars of Switchgrass

• ‘Blue Tower’ – up to 8 feet tall in flower, blue-green leaves, selected by Crystal Palace Perennials of Illinois

• ‘Cloud Nine’ – is a tall selection introduced by former Bluemount Nursery of Maryland that can reach 7-8 feet, with light metallic blue leaves and gold fall color. It makes a good substitute for some of the larger Miscanthus cultivars. Hardy to zone 4a.

• ‘Dallas Blues’ – is a 5 foot tall selection originally found in Dallas and introduced by Change of Scenery Nursery in Columbus, Ohio. It has powdery blue leaves that turn copper in fall and remain well colored through the winter, and pinkish-purple flower plumes. The leaves are wider than many other cultivars, and plants have a fuller shape and denser flower spikes that appear in distinct layers. It is more drought tolerant than many cultivars. Patented (USPP 11,202) in 2000.

• ‘Heavy Metal’ – a Kurt Bluemel introduction with tightly upright blue-green leaves that turn rich amber in fall and fade to light tan by winter. The compact plants are only about 3-5 feet tall, has flower spikes with strong pink tones, and dark burgundy seeds. Hardy to zone 4a.

• ‘Northwind’ – is a vigorous, very upright selection by Roy Diblik at Northwind Perennial Farm in Burlington, Wisconsin, growing up to 5 feet tall with steel blue foliage that turns tawny gold in fall, and maroon and green flower plumes held erect above the foliage.

• ‘Prairie Fire’ – from Amber Wave Gardens, Benton Harbor, Michigan has green foliage that turns shades of deep red in early summer – much earlier than other red cultivars – and butter yellow in fall. The upright clumps grow 4-5 feet tall and 1½-2 feet wide. the leaves curl slightly when the rosy panicles appear.

• ‘Prairie Sky’ – discovered growing wild in a Wisconsin meadow, it is one of the bluest selections (but not as sturdy as some so it may flop more in wet conditions) that grows 4-5 feet tall, with silvery inflorescences.

• ‘Rehbraun’, ‘Rotstrahbusch’ – Both of these early blooming cultivars feature airy seedheads containing red seeds and reddish fall color. Shorter than most, typically 3 to 4 feet tall.

• ‘Shenandoah’ – is a German selection that grows 3½-4 feet tall and has red leaf tips early in the growing season and burgundy fall foliage color with burgundy seedheads.

There are also a number of selections for agricultural or conservation use that were chosen for attributes other than their appearance.

– Susan Mahr, University of Wisconsin – Madison

Last Update: Bruce Spangenberg, UW-Madison Extension, 2025