Santa Fe Botanical Garden

Common name: 'Shenandoah' switch grass

Family: Poaceae (Grass)

Distribution: Cultivated

Hardiness: USDA Zone 4 (-30 to -20 °F)

Life form: Grasses

Occurrence in New Mexico: Cultivar

Growing Conditions: Switch grass was a major component of the tallgrass prairie that once covered large areas of the Great Plains. It occurs in both wet and dry soils, on gravel bars and stream banks. The cultivar ’Shenandoah’ is easy to grow and adapts to most soil types; but prefers semi-moist to wet sandy or clay soils. Regular watering during the first growing season helps establish an extensive root system. Once established, it tolerates mild drought as well as occasional flooding. It grows in full sun to partial shade; but prefers some shelter from intense late afternoon sun in hot climates. It grows primarily in clumps, but may lose its shape in overly rich soils or with too much shade. Cut back in late winter or early spring. Plants spread slowly by creeping rhizomes, and may self-seed, but offspring may not be identical to the parent plant. It is often planted as an accent plant in perennial borders, in meadows or naturalized areas, in water or bog gardens, along ponds, or in containers.

Description: Switch grass is a warm-season grass with a clumping, upright and columnar form. It is taller than other members of the genus; this cultivar grows 3-6 tall (including flower stalks) and 2-3 feet wide. The leaves are green in spring, become coarser and tipped with reddish purple in summer, and change to a solid reddish purple by autumn. The leaves are spaced alternately along the entire length of the stout culms. The leaves are about 2 feet long, flat or slightly indented along their midveins. The leaf sheaths have V-shaped openings at the apices. The 7-20 inch long influorescence is an airy, weeping panicle of pinkish or purplish green spikelets. The central stalk (rachis) divides into widely spreading branches and branchlets with stalked spikelets. Each spikelet has a perfect floret, surrounded by modified leaf bracts (glumes and lemmas) that are about the same length as the floret. Mature spikelets fall in their entirety; however, the seedheads usually persist throughout winter. The root system is fibrous and rhizomatous, and may be up to 10 feet deep.