Cheatgrass (Downy Brome)
Bromus tectorum · Cool-season winter annual, C3
Grass Family
Poaceae, Pooideae, Tribe Bromeae
Grass Category
Invasive/Weed Grass, Fire Hazard
Variety / Cultivar
None (Wild type/Ecotype)
Hardiness Zones
USDA Zones 3-11; highly adaptable but thrives in regions with winter precipitation and dry summers.
About This Grass
An aggressive winter annual that germinates in autumn or winter. It grows rapidly in spring, turning reddish-purple before drying to a tan color by early summer. It reaches 4 to 30 inches in height. The inflorescence is a drooping, branched panicle with long awns (bristles).
Blade Characteristics
Fine to medium width (2-5mm), flat, light green to reddish, covered in soft, dense hairs (downy). Vernation is rolled; ligule is membranous and fringed; auricles are absent.
Root System
Shallow, fibrous root system that effectively outcompetes native perennials for early spring moisture. Lacks rhizomes or stolons.
Growing Information
Origin Region
Europe, North Africa, and Southwestern Asia; highly invasive in the Intermountain West and Great Basin of North America.
Growth Habit
Bunch-type (clump-forming), solitary or in small tufts with high seed production.
Sunlight & Water Needs
Full sun to partial shade; flourishes in arid and semi-arid conditions; low water requirements and extremely drought tolerant once established.
Mowing & Maintenance
Low maintenance as a weed; mowing is only used to reduce fire risk or prevent seed set. Must be mowed before seed heads emerge. High maintenance to eradicate.
Special Characteristics
Highly flammable when dry, creates a wildfire cycle; seeds have sharp awns that can injure the mouths and eyes of livestock and pets.
Ecological Information
Invasive status; significantly alters ecosystems by increasing fire frequency; provides limited early spring forage for wildlife but generally degrades native habitats.