Johnsongrass
Sorghum halepense · Warm-season, Perennial, C4 grass
AI-generated identification · may be incorrect
Grass Category
Invasive/Weed Grass, Pasture/Forage Grass
Hardiness Zones
Thrives in USDA Hardiness Zones 6 through 10. Excellent heat tolerance, moderate cold tolerance for a warm-season grass, and goes dormant in winter with dead topgrowth.
Grass Family
Poaceae, subfamily Panicoideae, tribe Andropogoneae
Variety / Cultivar
Wild type (No specific cultivated varieties for turf; highly variable wild populations)
About This Grass
A tall, coarse perennial grass that can reach heights of 3 to 7 feet (approx 1 to 2 meters) or more when left unmowed. Features bright to dark green leaves with a prominent whitish midrib, thick purplish-tinted lower stems, and large open panicle seed heads.
Blade Characteristics
Coarse blades ranging from 0.5 to 1 inch wide, flat shape, pointed tip, bright to dark green color often with a whitish or light green midvein, rolled in the bud (vernation). Membranous ligule, lack of auricles, and a distinct prominent collar region.
Root System
Deep, aggressive fibrous root system combined with thick, fleshy, scaly rhizomes that can penetrate deeply into the soil. High thatch tendency, extremely rapid establishment, and forms dense, persistent colonies.
Growing Information
Origin Region
Native to the Mediterranean region and parts of Asia; naturalized globally in temperate, subtropical, and tropical regions.
Growth Habit
Aggressively spreading via both extensive underground rhizomes and seeds, forming dense patches or clumps.
Sunlight & Water Needs
Requires full sunlight for optimal growth. Moderate water requirements once established, but highly drought-tolerant due to deep root and rhizome system. Prefers rich, moist soils but adapts well to diverse soil types and pH levels.
Mowing & Maintenance
Difficult to control by mowing alone due to rapid vertical growth and persistence of rhizomes. Requires frequent mowing below growing points, intensive management, or targeted herbicide use. High maintenance when treated as a weed.
Special Characteristics
High wear and drought tolerance, highly invasive weed in agricultural settings, can produce toxic cyanogenic glycosides (prussic acid) under stress (drought/frost) when grazed by livestock. Difficult to eradicate once established.
Ecological Information
Introduced species in North America, often considered a noxious invasive weed due to outcompeting native vegetation and crops. Provides limited wildlife cover but can poison grazing livestock under specific stress conditions.