Roughstalk bluegrass. Photo: Mira Talabac, University of Maryland Extension

Roughstalk bluegrass (Poa trivialis), the light green patches in a residential lawn. Photo: M. Talabac, University of Maryland Extension

Updated: February 21, 2024

Roughstalk bluegrass or rough bluegrass (Poa trivialis) is a common grassy perennial weed in Maryland lawns. It is most noticeable in the springtime. It has a light green color and fine texture that does not blend well with typical tall fescue lawns during the spring and early summer. It grows faster and outcompetes more desirable turf grasses.  

Life cycle

Perennial, cool-season grassy weed. Thrives in early spring and fall. 

Growth habit 

Roughstalk bluegrass is an aggressive, clumping spreader. It forms yellow-green patches in spring and summer and has white trailing tillers (side shoots at the ground level). Grass blades sometimes look shiny on the underside. The stalks can turn red at the base as the plants grow. Seedheads are produced in May-June.

Poa trivialis tends to go dormant during droughts and in the summer, leaving thin areas in the turf before re-growing in the cooler fall season. Also, heavy rainfall followed by hot sunny weather causes this grass to collapse into brown, dead-looking mats. Plants can regenerate from viable buds at the stem bases and may recover by late fall or the following spring. 


Roughstalk bluegrass often comes in as a contaminant in grass seed mixes. It spreads by reseeding from established plants and aggressive horizontal stolons.

seed head of rough stalk bluegrass
Seed head produced by Poa trivialis
Photo: David L. Clement, University of Maryland Extension

Conditions that favor growth

It prefers semi-shady conditions in compacted, poorly drained, moist soils (often beginning in drainage swales). Once established, it will spread into sunnier, drier sites. 

roughstalk bluegrass coming out of dormancy
Roughstalk bluegrass has a yellow-green color in early spring
roughstalk bluegrass ligule
Roughstalk bluegrass has a membranous ligule.
Photo: David L. Clement, University of Maryland Extension

Management in lawns

Lawn care practices

Maintain healthy, dense turf that can compete and prevent weed establishment.

Unfortunately, the seeds can be found in grass seed mixtures, even in the best blends. 

Lawn Care

Mechanical management

Small infestations can be dug out; all parts of the root must be removed. Rent a sod cutter to remove large patches. Then reseed with tall fescue or put down sod. This can mask the problem but may not eliminate it if seeds are present in the soil or come from another source.

Manage Weeds Without Chemicals

Chemical treatment in lawns

Perennial grasses growing out of place in lawns are extremely difficult to control selectively in turfgrasses. Roughstalk bluegrass cannot be effectively removed with any herbicides currently on the market. Total lawn renovation or killing the patches using glyphosate (an ingredient in a non-selective herbicide) and then reseeding will slow it down, but because of the vast seed bank in the soil and creeping stolons, it will return.

Lawn Herbicides for Weed Management

Additional resources

Rough Bluegrass Can Be Your Worst Lawn Nightmare | Dr. Peter Dernoeden, Professor Emeritus, University of Maryland

Poa trivialis | NC State (good for identification)

Roughstalk Bluegrass | Purdue University

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