Johnsongrass
Sorghum halepense · Warm-season, Perennial, C4 grass
AI-generated identification · may be incorrect
Grass Category
Invasive/Weed Grass, Pasture/Forage Grass
Hardiness Zones
USDA Hardiness Zones 6 through 10; highly sensitive to heavy frost which causes winter dormancy, though rhizomes survive underground.
Grass Family
Poaceae, subfamily Panicoideae, tribe Andropogoneae
Variety / Cultivar
Wild type (no specific ornamental or turf cultivars commonly recognized as standard)
About This Grass
A tall, aggressive perennial grass growing up to 3 to 7 feet high with thick stems. Features wide, light to medium green leaves with a prominent white midrib and large, open, purplish to grayish panicle seed heads.
Blade Characteristics
Coarse blades, typically 0.5 to 1.5 inches wide, flat, with a sharp, pointed tip and a distinct white midrib. Rolled vernation in bud. Ligule is a membranous fringe with fine hairs, and auricles are absent.
Root System
Extensive, deep, and aggressive fibrous root system combined with thick, fleshy, scaly rhizomes that store nutrients and spread rapidly, providing high drought resistance and making eradication difficult.
Growing Information
Origin Region
Native to the Mediterranean region and Asia; naturalized globally in warm-temperate and tropical regions
Growth Habit
Rhizomatous and stoloniferous, forming dense colonies and tall, coarse clumps
Sunlight & Water Needs
Requires full sun for optimal growth. Moderate to high drought tolerance once established due to deep roots. Thrives in fertile, well-draining soils but adapts to a wide range of soil pH and types.
Mowing & Maintenance
High maintenance if controlled as a weed, requiring frequent cutting or systemic herbicides. When used as forage, managed by rotational grazing or haying. Not suitable for standard turf.
Special Characteristics
High weed invasiveness, rapid spread via rhizomes and seeds. Contains dhurrin which can release toxic hydrogen cyanide (prussic acid) under drought or frost stress when grazed by livestock.
Ecological Information
Introduced species in North America, often classified as a noxious, invasive weed in agricultural fields. Provides limited cover for wildlife but can outcompete native vegetation, reducing biodiversity.