Switchgrass

Thrives in USDA Zones 3 - 9

• Transplant

  Plant container transplants in spring after last frost or in early autumn. Space 3-4 feet apart; switchgrass spreads slowly by rhizome and self-seeds modestly. Upright cultivars like Heavy Metal and Northwind hold their form without flopping.

• Harvest

  Leave standing through winter for birds and structure; cut back to 4-6 inches in late winter before new growth emerges. Switchgrass can be slow to emerge in spring - wait before assuming winter loss.

• Switchgrass grown in lean soil and full sun will be upright and compact; in shade or rich soil it will flop. Site selection matters more than pruning for good form.

• Divide clumps in early spring every 5-7 years to reinvigorate; transplant divisions immediately.

• The straight species self-seeds more freely than named cultivars; cut back before seed fully ripens if you want to limit spread.

• Watering

  If dry weather lingers, let the top 2 inches start to dry before watering again. This plant often responds better to an occasional deep soak than to frequent light watering.

• Feeding

  If growth is strong, compost-rich soil often carries most of the load. If the plant starts looking pale or stalls, a light compost top-dressing or gentle organic feed may help.

• Seasonal care

  In late fall, a light cleanup and fresh mulch can help if winter protection is useful in your climate. Leaving a little space around crowns and trunks often helps air move and keeps excess moisture from sitting there.

• Harvest timing

  Harvests often cluster around January, February, November, December. If fruit, leaves, or roots start looking ready, color, size, firmness, and scent usually tell you more than the calendar alone.

• Shenandoah

  The most popular cultivar; outstanding burgundy-red fall color beginning in August; compact at 3-4 feet. Named after Shenandoah National Park. The best choice for small gardens and containers.

  Best for

  Fall color; smaller gardens; containers

• Heavy Metal

  Strongly upright, almost columnar habit; steely blue summer foliage; yellow fall color. Holds its form without staking even in partial shade. Classic for formal or modern landscapes.

  Best for

  Formal gardens; upright habit; blue foliage

• Northwind

  The most upright of all switchgrass cultivars; remains bolt-upright even in wind and partial shade; olive-green foliage, yellow fall color; 5-6 feet tall. Best for screening.

  Best for

  Screening; windy sites; most upright habit

• Dallas Blues

  Large cultivar (5-6 feet) with pronounced blue foliage and large showy panicles; selected from Texas populations for superior heat tolerance and performance in the South.

  Best for

  Zones 6-9; heat tolerance; blue foliage; large-scale plantings

• Rust (minor)
• Smut (rare)

Origin

Native across most of eastern and central North America, from Nova Scotia and Manitoba south through the Great Plains to Mexico, and east to the Atlantic and Gulf coasts.

Native Habitat

Tallgrass and mixed-grass prairies, coastal salt marshes, pine savannas, open woodlands, and disturbed sites on a wide range of soils from wet to dry.

Current Distribution

Abundant in remnant prairies and coastal marshes; widely cultivated as an ornamental throughout North America and Europe; significant research interest as a bioenergy crop.

Kingdom

Plantae

Family

Grass family (Poaceae)

Genus

Panicum

Species

Panicum virgatum

• Root System

  Deep fibrous root system with rhizomes; roots documented to 11 feet; extensive lateral root network; among the deepest-rooted grasses in North America.

• Stem

  Upright to slightly arching culms 3-6 feet tall; cultivar dependent; green in summer, aging to tan and buff in winter.

• Leaves

  Flat, linear blades 1/4 - 1/2 inch wide; green to blue-green in summer; fall color ranges from yellow to deep burgundy by cultivar.

• Flowers

  Open, airy panicle inflorescence 12-18 inches long; initially pinkish-red to purple, drying to golden tan; floats above foliage in late summer.

• Fruit

  Small ovoid grain; produced in quantity on the open panicles; important food for birds including juncos, sparrows, and towhees.

Panicum virgatum was a dominant grass of the tallgrass prairie, one of the most productive grassland ecosystems on Earth, covering approximately 170 million acres of central North America before European settlement. It co-dominates with Big Bluestem and Indian Grass in the tallgrass, and extends into the coastal salt marshes of the Atlantic and Gulf coasts - a remarkable ecological range. Its deep root system (up to 11 feet in some studies) makes it one of the most important carbon-sequestering plants in North America, and switchgrass prairie soils accumulated the extraordinary depth of organic matter that made the Great Plains the most productive agricultural region in the world. The species achieved renewed scientific prominence in the early 2000s as the leading candidate for cellulosic biofuel production, with significant federal research investment into high-biomass cultivars. Simultaneously, the ornamental horticulture industry was developing garden cultivars with improved form and color, and switchgrass is now among the most commonly planted native grasses in designed landscapes throughout North America and Europe.