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Bothriochloa torreyana

silver bluestem

Poaceae South-central North America

Drought Tolerant

Native to North America

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 5–9

Overview

Bothriochloa torreyana is a native warm-season perennial bunchgrass in the family Poaceae, forming erect tufts 1.5-4 feet (45-120 cm) tall from a firm crown. The narrow leaf blades are 4-10 inches (10-25 cm) long and blue-green, drying to tan in autumn. From mid-summer into fall the stems are topped by a narrow, feathery seed head 2-5 inches (5-13 cm) long, made up of branches densely clothed in silvery-white silky hairs that give the grass its common name. The hairy seed heads catch the light and aid wind dispersal of the small seeds. B. torreyana grows on dry prairies, limestone hills, roadsides, and open rangeland across the south-central United States and northern Mexico, where it tolerates heat, drought, and poor, rocky soils. It greens up in late spring, flowers through the summer, and goes dormant after frost. As a bunchgrass it supplies only fair forage and is grazed mainly when young, becoming coarse and less palatable with age. It establishes readily on disturbed ground and can increase on overgrazed range where more palatable grasses decline.

Native Range

Native to the south-central United States and northern Mexico, from Kansas and Colorado south through Texas and New Mexico into Coahuila and Chihuahua. It occurs on dry prairies, rocky limestone slopes, mesas, roadsides, and disturbed open ground.

Suggested Uses

Used in native prairie restoration, rangeland seeding, and erosion control on dry, rocky, or disturbed ground. The seed heads add late-season texture to native and xeriscape plantings. It supplies cover and seed for grassland birds and small wildlife.

How to Identify

Recognized by its narrow, feathery, silvery-white seed head in which the branches are crowded with long silky hairs. The grass grows in erect tufts with blue-green blades that cure to tan. Unlike the finger-like racemes of King Ranch bluestem, the seed head is a single narrow plume rather than a spreading cluster. The dense silvery hairs and slender form distinguish it on dry, open sites.

Appearance

Size & Dimensions

Height1'6" - 4'

Width/Spread1' - 1'6"

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~16 weeks

Summer Fall

Flowering runs from mid-summer into fall, mainly July through October, following warm-season rains. New flowering culms continue to rise over several weeks, so plants often carry seed heads at varied stages. The silvery seed heads persist on the plant well after the seeds ripen.

Detailed Descriptions

Foliage Description

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 Range6.0 - 8.0(Neutral)

357912

Soil Types

sand loam clay rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

establishes within one to two seasons

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Bothriochloa torreyana grows in full sun on dry, well-drained sandy, loamy, clay, or rocky soils with a pH near 6.0 to 8.0, including shallow soils over limestone. It is drought and heat tolerant once established and needs no irrigation or feeding. The grass is hardy in roughly USDA zones 5 to 9 and dies back to the crown after hard frost, regrowing in late spring. It reseeds onto bare ground and can increase under heavy grazing as more palatable grasses are removed. Periodic mowing or grazing keeps stands open, while old growth can be cleared in late winter.

Pruning

No routine pruning is needed. Old foliage and spent seed stalks can be mowed or cut back in late winter before new growth emerges. Cutting before seed heads ripen limits self-sowing where spread is unwanted.