Big Bluegrass

NRCS Plant Materials Center, Pullman, WA
Scientific name: 

Poa secunda (formerly Poa ampla Merr.)

Native Grass
Annual precip. min (mm): 
Annual precip. max (mm): 
Seed size: 
Seeds per kg: 
PR Suitability note: 
Sandberg's bluegrass is found in grassland plant communities in the Peace Region, limited mostly to steep south facing slopes along the main river valleys. However "Shermans" big blue grass is selected from Oregon, and is substantially different in form than BC's native Sandberg's bluegrass.
Key considerations: 
If there is a native plant community objective explore seed options sourced from local ecotypes.
General Description: 

Big bluegrass is a native, cool season, long-lived, perennial bunchgrass that matures early in the growing season. It is part of what is referred to as the Sandberg bluegrass complex, which includes 8 species, including big bluegrass, Canby bluegrass, slender bluegrass, Alkali bluegrass, Nevada bluegrass, Sandberg bluegrass, and pine bluegrass. The differentiating characteristics within this complex of species often vary with environmental factors, making distinguishing amongst them very difficult. Big bluegrass is the most robust of this collection, and stands out for its large forage production and early spring growth. It has been used successfully for reseeding burned forest areas and is used by upland game birds for nesting.

Big bluegrass is a bunchgrass with a strong fibrous root system that sometimes develops short rhizomes. The rooting system is very effective in controlling soil erosion, thus this species is considered a good conservation grass. “Sherman” big bluegrass is a selection originating from seed collected from a native range site in Sherman County, Oregon. It has been successfully established in the Rocky Mountain regions of the United States above 2,100 m in elevation that receive above 360 mm (14 in.) of rainfall, and the Columbia Basin.

Stems grow to 30 to 130 cm (12 to 51 in.) in height. It has distinctly deep blue-green, abundant basal leaves. The leaf blades are folded in a keel-like tip typical of all bluegrasses. Leaves can grow up to 40 cm (16 in.) long and 1.5 to 3.5 mm (1/16 to 1/8 in.) wide.

Seeds develop in a large compact seed head with narrow panicle that is 20 cm (8 in.) long. The spikelets of big bluegrass (and the entire Sandberg bluegrass complex) differ from Kentucky bluegrass in that they do not have a web of hairs at the base of the seed callus.

Big bluegrass is native to North America.
Occurs mainly in western North America with some specific populations in Quebec and Chile. The big bluegrass type of Poa secunda appears to be rare in British Columbia. The Poa secunda form known as Sandberg bluegrass is common.
Habitat and climate: 
Big bluegrass occurs in sagebrush slopes, mid-elevation meadows, and openings in aspen stands.
Big bluegrass is used for forage, dryland hay, and upland wildlife habitat. Upland game birds eat the seeds and use big bluegrass for nesting areas. It is also an important species for reseeding rangelands, stabilizing critical areas, reclaiming mine soils, and revegetating disturbed areas in aspen and conifer forests. Collections in Alaska have been used for erosion control, reclamation, and native plant community restoration.
Optimal time of grazing use: 
Big bluegrass begins growing very early in the spring and up to 4 weeks earlier than crested wheatgrass. However, grazing on newly establishing stands should be deferred for 1 to 3 years.
Recovery after use (rating): 
Recovery after use: 
Big bluegrass is considered an increaser species after grazing. It resists trampling very well as it goes dormant during summer and fall.
Forage yield (rating): 
Forage yield: 
Forage production from big bluegrass varies, especially with rainfall and irrigation. Areas with at least 280 mm (11 in.) of rainfall can yield 630 to 1,360 kg/ha (562 to 1,214 lb/acre).
Palatability/Nutritional Value: 
Palatable for livestock in spring and fall, for deer in the spring, and for elk in all seasons. As curing progresses over the summer, livestock preference for big bluegrass decreases.
Longevity (rating): 
The longevity of big bluegrass stands can exceed 30 years. This is partially due to seed shatter and the prolific “reseeding” of this plant species.
Persistence (rating): 
Invasiveness (rating): 
Seeds shatter but do not travel far from parent plant. Although big bluegrass seed can spread through feces, it is not considered aggressive or invasive.
Competitiveness (rating): 
It is often used as an early spring perennial grass that will compete well with annual weeds. Once established, big bluegrass, especially the Sherman variety, competes well with other weeds such as cheatgrass, Russian thistle, and prickly lettuce.
Weed resistance (rating): 
Erosion control (rating): 
Drought tolerance (rating): 
Drought tolerance: 
Does not tolerate drought as well as other cool season grasses.
Winter hardiness (rating): 
Winter hardiness: 
Big bluegrass is rated with excellent cold tolerance but this rating is from the lower Columbia Basin in the U.S. Pacific Northwest where winters are milder than in many parts of British Columbia.
Soil texture preference (rating): 
Soil texture preference: 
Thrives on a variety of soil textures from moderately coarse sands to dense clays.
Flooding tolerance (rating): 
Flooding tolerance: 
Although it will grow in moist conditions, it will not tolerate early spring flooding, poor drainage, or high water tables.
Salinity tolerance (rating): 
Acidity tolerance (rating): 
Acidity tolerance : 
Sherman big bluegrass tolerates moderately acidic soils, thus it is a suitable species for reclaiming mine spoils. It can also tolerate weakly alkaline soils.
Shade tolerance: 
Moderate shade tolerance
Pests and/or disease threats: 
Potential insect pests include grasshoppers, jackrabbits, and rodents. Disease threats include leaf rusts, stem rusts, and stem maggots.
Ease of establishment (rating): 
Ease of establishment: 
Some varieties of big bluegrass shatter easily and grow from scattered seed, thus stands can improve and fill in over time.
Application requirements: 
To ensure successful establishment of big bluegrass, perennial broadleaf weeds like Canada thistle and leafy spurge will have an impact on forage production and must be controlled before and after seeding. If seeding a pure stand, seed at 1.7 kg/ha PLS or pure live seed (2.0 lb/acre PLS). If seeding in a native seed mixture, as is more commonly done, seed at 0.3 to 0.6 kg/ha PLS (1/2 to 1 1/4 lb/acre PLS). Spring seeding is best in Northern Great Plains while late fall seedings are suitable in areas with similar climate to the Great Columbia Basin.
Suggested mixtures: 
Can be mixed with native fescues, wheatgrasses, and wildryes.
Management considerations: 
When seeded with other native plants, big bluegrass is often a minor component of the mix. Management of the stand should consider major species in the mix and overall seeding objectives.