To Grass Species

Mountain Bromegrass (Bromus marginatus)

Plant Species
From Montana Interagency Plant Materials Handbook *
S. Smoliak, R.L. Ditterline, J.D. Scheetz, L.K. Holzworth, J.R. Sims, L.E. Wiesner, D.E. Baldridge, and G.L. Tibke

Mountain bromegrass is a cool-season, native bunchgrass of the northern and central Rocky Mountains regions and the northern part of the intermountain region. Mountain bromegrass is a short-lived species with good seedling vigor. It has been used in mixtures with sweetclover or red clover for pasture or green manure in short rotations. It can also be used to stabilize road cuts and fills or mined lands where rapidly-developing seedings are needed.

Mountain bromegrass has been placed in a group of grasses classified as: "Rapid developing, short-lived grasses." Other grasses in this group are slender wheatgrass, Canada wildrye, blue wildrye and perennial ryegrasses.


Mountain bromegrass is a short-lived, perennial bunchgrass. It reaches maximum seed and forage production the second season after sowing; hence it does well with sweetclover. Mountain bromegrass has an extensive, fibrous root system that is effective in controlling soil losses. The grass is high in crude protein and digestible carbohydrates.


Mountain bromegrass can be grown throughout the intermountain areas of the Pacific Northwest, except in areas where the annual precipitation is less than 16 inches. It is well adapted to this area since mountain bromegrass is a part of the native vegetation on the better sites. It seems to thrive with climatic conditions of a cool, dry summer and adequate winter precipita-tion.

Mountain bromegrass and other grasses such as slender wheatgrass, Canada and blue wildrye, and perennial ryegrass have strong seedling vigor. They establish readily, develop readily, provide good cover and often make a seed crop in the year they are planted. They equal and often exceed the production of other grasses the season following the planting year. They decline rapidly in vigor and production, are not drought resistant and perform poorly or die during years of below average precipitation. These grasses are most useful for rapid temporary cover or use as a nurse crop in mixtures with other perennial grasses.


Mountain bromegrass is a short-lived species and must depend on natural seeding for longevity. Seed must be treated with a fungicide before planting because this grass is very susceptible to head smut. It reaches maximum seed and forage production the second year after seeding, with third and fourth year yields being low. Plants lose vigor and start to die out after the second year under average use conditions. The seed of mountain bromegrass should not be covered with more than one inch of soil.

Use for Hay

Mountain bromegrass is not suited for permanent hayland plantings because of the extreme drop in production after the second year. It is much more suited to mixtures used to stabilizing road cuts and fills, mined lands, green manure crops and other uses where rapidly developing seedings are needed.

Use for Pasture

Mountain bromegrass has been used in mixtures with sweetclover or red clover for pasture in short rotations. Production drops drastically the third and fourth year after seeding, which makes mountain bromegrass a very poor choice for permanent pastures.

Seed Production

Mountain bromegrass is considered a good seed producer and is easy to maintain because it is self-fertile. Since the seed shatters, care must be taken when harvesting. At least two seed crops may be obtained from one sowing, providing that weeds are kept in check and the stand of grass does not suffer severe winter injury between the second and third years of production.

* The Montana Interagency Plant Materials Handbook (EB69) is no longer in print, but is available for viewing in
Montana County Extension Service and National Resource Conservation Service Offices.