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Panicum spp.

panicgrasses

Poaceae

Worldwide in warm temperate and tropical regions

Deer Resistant Drought Tolerant

Native to North America

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 5–11

Overview

Panicum spp. is a large genus of roughly 450 warm-season grasses in the family Poaceae, distributed across tropical and temperate regions worldwide, with strong representation in the Americas. The genus spans short annual species a few inches high to robust perennials reaching 3-10 ft (0.9-3 m), forming either tight clumps or spreading colonies from rhizomes depending on species. Leaf blades are flat, 4-24 inches (10-60 cm) long and 0.1-1 inch (0.3-2.5 cm) wide, ranging from green to blue-green and turning yellow to russet in autumn on temperate perennials such as switchgrass (P. virgatum). Flowers are borne in open, branched panicles 4-20 inches (10-50 cm) long, the individual spikelets small and two-flowered, and airy seed heads follow that persist into winter on perennial species. As C4 grasses, members of Panicum spp. photosynthesize efficiently in heat and full sun and grow most actively from late spring through summer. Several species are grown for forage, soil stabilization, and biofuel, while others, including P. repens and weedy annual panicums, spread aggressively in cultivated ground and wetlands. Cold tolerance, mature size, and lifespan vary widely across the genus.

Native Range

Distributed worldwide across warm temperate and tropical regions, with the greatest diversity in the grasslands and open woodlands of the Americas. Switchgrass (P. virgatum) is native to the North American prairies and ranges from Canada to Mexico.

Suggested Uses

Used in prairie and meadow plantings, rain gardens, and erosion control on banks and roadsides, with perennial species also grown as forage and biofuel crops. The persistent seed heads feed seed-eating birds through winter. Spreading and weedy species are managed rather than planted where they naturalize.

How to Identify

Identified by warm-season growth, flat leaf blades, and large, open, much-branched flower panicles that give the seed heads an airy, cloud-like outline. The small spikelets are two-flowered, with the lower floret sterile or staminate and a hardened, shining upper floret enclosing the grain. Clump-forming perennials such as P. virgatum build upright tussocks, while species like P. repens run on creeping rhizomes.

Appearance

Size & Dimensions

Height6" - 10'

Width/Spread1' - 4'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

red

Bloom Information

Bloom Period

~10 weeks

Summer Fall

Flowering occurs mainly in summer and early autumn (July-October) once temperatures are consistently warm. Panicles open above the foliage and shift from green to straw and bronze as the seed ripens. Wind carries the pollen, and ripe seed heads on perennial species hold through autumn and winter.

Detailed Descriptions

Flower Description

Green to tan

Foliage Description

Green to blue-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.5(Neutral)

357912

Soil Types

sand loam clay silt

Drainageaverage

Water & Climate

Water Needs

Low

Time to Maturity

1-3 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Grow in full sun in a wide range of soils, from sand to clay; most species withstand poor fertility, drought, and brief flooding once established. Switchgrass and similar perennials hold their upright form in lean soil and open sun, while rich soil and shade cause the stems to flop. Watering is rarely needed for established perennials outside extended drought. Hardiness varies by species, with P. virgatum growing in USDA zones 5-9 and many tropical panicums limited to frost-free zones 9-11. Spreading species can move beyond their intended area through rhizomes and self-sown seed. Annual panicums complete their cycle in one season and return from seed.

Pruning

On perennial species, old foliage is cut back to a few inches above the crown in late winter before new growth begins. The dried stems and seed heads stand through winter until that cut. Annual species need no pruning and die with the first hard frost.