If your lawn looks lush and green in the spring but develops brown, thin, or patchy areas during the summer, rough bluegrass may be the culprit.
Rough bluegrass (Poa trivialis) is a cool season perennial grass that is commonly found in lawns throughout Minnesota and Wisconsin. While it can look very similar to Kentucky bluegrass during cooler weather, its poor heat tolerance often causes it to stand out dramatically during the summer months.
Because rough bluegrass behaves differently than desirable lawn grasses, homeowners are often surprised when patches suddenly turn brown even though the rest of the lawn remains green.
What Is Rough Bluegrass?
Rough bluegrass is a perennial grass species that spreads through above ground runners called stolons. Unlike Kentucky bluegrass, which spreads through underground rhizomes, rough bluegrass tends to create patches with a matted or laid over appearance.
It is commonly introduced into lawns through seed or sod. Historically, rough bluegrass has often been included in inexpensive or shade tolerant seed mixes because its seed is difficult to separate from Kentucky bluegrass seed.
Rough bluegrass performs very well during the cool temperatures of spring and fall. In fact, many homeowners do not notice it until summer arrives.
How to Identify Rough Bluegrass
Rough bluegrass is commonly identified by a combination of characteristics:
- Bright green color during spring and fall
- Patches that appear softer and more matted than surrounding turf
- Above ground runners that allow it to spread
- Rapid decline during hot summer weather
The most noticeable characteristic is its seasonal behavior. During summer heat, rough bluegrass often turns purple, tan, or brown while nearby Kentucky bluegrass remains green. The affected areas can look dead, but the grass is usually dormant rather than dead. Once cooler temperatures return in late summer or fall, the grass often greens up again.
Common Misconceptions About Rough Bluegrass
One of the biggest misconceptions is that rough bluegrass is a lawn disease.
Homeowners frequently notice patches turning brown during summer and assume disease, insect damage, fertilizer injury, or drought stress is the cause. While those issues can certainly occur, rough bluegrass naturally declines during hot weather because it has poor heat tolerance.
Another misconception is that there is a selective treatment available.
Unfortunately, rough bluegrass is closely related to Kentucky bluegrass and other desirable lawn grasses. Because of these similarities, there are currently no practical selective herbicides available for home lawns that will remove rough bluegrass without also damaging desirable turf.
What Can a Homeowner Do If They Have Rough Bluegrass?
Homeowners generally have four options:
Option 1: Live With It
Many homeowners choose to tolerate rough bluegrass.
The lawn will often look excellent during spring and fall. While the patches may become brown or thin during summer, they usually recover when temperatures cool.
Option 2: Improve Conditions
Maintaining proper irrigation during hot weather can help reduce summer stress and dormancy.
While watering will not eliminate rough bluegrass, it may reduce the severity of summer browning.
Option 3: Remove It by Digging
For smaller patches, physical removal is often effective.
Remove the rough bluegrass and surrounding area, extending at least 12 inches beyond the visible patch. Because stolons can spread beyond what is visible, it is important to remove a generous margin around the infestation. Replace the removed soil with clean soil and then seed or sod the area.
Option 4: Kill and Renovate the Area
For larger infestations, many homeowners choose to spray the affected area with a non selective herbicide such as glyphosate.
The treatment area should extend 6 to 12 inches beyond the visible patch. Two applications are often recommended to ensure complete control. Once the grass has died, the area can be reseeded or resodded.
What Can bioLawn Do If You Have Rough Bluegrass?
Currently, bioLawn does not offer rough bluegrass removal services.
However, we can:
- Help identify rough bluegrass
- Confirm whether rough bluegrass is causing summer decline
- Provide recommendations on removal and renovation options
What Can Homeowners Do to Prevent Rough Bluegrass?
Prevention is much easier than removal.
When seeding a lawn, choose high quality seed from reputable suppliers and carefully review seed labels. Avoid inexpensive seed blends that may contain rough bluegrass or other undesirable grasses.
When installing sod, purchase from reputable growers that maintain high quality standards.
What Can bioLawn Do to Prevent Rough Bluegrass?
Unfortunately, there are no lawn care treatments that prevent rough bluegrass from becoming established once it is introduced.
Our role is primarily educational and diagnostic. We can help identify the issue early, provide management recommendations, and assist with renovation planning when removal becomes necessary.
Final Thoughts
Rough bluegrass is one of the more frustrating invasive grasses found in home lawns. It blends in with desirable turf during spring and fall but often becomes highly noticeable during the heat of summer.
Because there are no selective control options available, management typically comes down to either living with it or removing and renovating the affected area.
If you’re seeing bright green patches in spring that turn brown every summer, rough bluegrass may be the cause. Our team is happy to help identify the problem and discuss the best options for your lawn.