Bulbous bluegrass is unique because it fails to produce true seeds. This perennial grass reproduces vegetatively in two ways. It grows from basal bulbs to form closely clustered bunches of stems up to 2 feet tall. The bulbs multiply by sending new bulbs out laterally.

In addition, the flowers produce bulbils rather than seed. The dark purple bulbils contain a rudimentary plant that does not develop until after an extended dormant period. Fields of mature bulbous bluegrass have a dark purplish cast. The heads droop over with their heavy load of bulbils.

The leaf blades are narrow, hairless, flat or loosely rolled, with membranous ligules about 1/8 inch long. A thick stand of bulbous bluegrass has a bright, light green appearance in the spring. The inflorescence is a moderately dense panicle of awnless spikelets.

Bulbous bluegrass is not an aggressive competitor in good stands of perennial crops such as pastures and alfalfa. Establishment of a competitive perennial grass in uncropped land or rotation from annual crops to permanent pasture or alfalfa will help prevent spread and is a good management strategy for an existing population.

In areas where the weed has already become established, it is important to stop production of new bulbs and bulbils. Heavy grazing, tillage, and selective herbicides are effective control methods. Seed new crops in the spring when possible to allow destruction of the bulbous bluegrass plants that start in the fall and winter.

For chemical control recommendations, refer to the Pacific Northwest Weed Control Handbook, an annually revised Extension publication available from the Extension bulletin offices of Oregon State University, Washington State University, and the University of Idaho