Cheatgrass (Downy Brome)
Bromus tectorum · Cool-season, Annual, C3
Grass Family
Poaceae, Subfamily Pooideae, Tribe Bromeae
Grass Category
Invasive/Weed Grass, Invasive Meadow/Rangeland Grass
Variety / Cultivar
Common (Wild-type species)
Hardiness Zones
USDA Zones 3-11; extremely cold hearty as a winter annual. Germinates in autumn or early spring, completes life cycle by early summer and becomes dormant/dead straw.
About This Grass
A prolific annual grass that matures and turns reddish-purple to tan-brown very early in the season. It typically reaches 6 to 24 inches in height. It is characterized by its drooping, nodding panicles with long-awned spikelets that give the plant a 'fuzzy' or 'downy' appearance.
Blade Characteristics
Blades are 2-4mm wide, flat, and covered in soft, dense hairs (pubescent) giving a soft feel. Tips are pointed. Color is light green during early growth, turning reddish-purple at maturity. Vernation is rolled. The ligule is membranous and often frayed; auricles are absent.
Root System
Shallow, fibrous root system; lacks rhizomes or stolons. Its primary strategy is rapid spring growth to deplete soil moisture before other plants can establish. Minimal thatch but high straw/litter production.
Growing Information
Origin Region
Native to Europe, Southwestern Asia, and Northern Africa; highly invasive in Western North America and temperate regions worldwide.
Growth Habit
Bunch-type (clump-forming); strictly annual spreading via heavy seed production rather than vegetative structures.
Sunlight & Water Needs
Full sun to partial shade; highly adaptable to dry, disturbed soils. Low water requirements; thrives in arid and semi-arid environments. Prefers alkaline to neutral soil pH.
Mowing & Maintenance
Maintenance is typically focused on eradication rather than cultivation. Mowing must occur before seed head emergence to prevent spread. Not a turf grass; requires frequent intervention to prevent fire hazards and livestock injury.
Special Characteristics
Low wear tolerance. Notable for 'foxtails' (awned seeds) that can cause mechanical injury to the eyes, mouths, and ears of livestock and pets. Highly flammable when dry, significantly increasing wildfire frequency in infested areas.
Ecological Information
Invasive status in North America; outcompetes native bunchgrasses by utilizing early-season moisture. Provides minimal wildlife forage after drying out. Known for creating an invasive-fire cycle that permanently alters ecosystems.