Knowledgebase
Lawn Grass identification #806021
Asked August 12, 2022, 9:56 PM EDT
Hennepin County Minnesota
Expert Response
Hi,
This may be barnyard grass, an annual grass. Using Roundup isn’t recommended unless you want to kill the entire lawn. Even then, seeds from the weedy grass will remain and pop up later. Rototilling wont solve the problem either.
Cultural practices like fertilizing your lawn to grow healthy competitive turf and raising the mower blade in the summer to let grass grow longer will help suppress the weedy grass.
Seeds last a long time in soil, so you may be dealing with this issue for awhile. You can pull the plants up or use a pre-emergent fertilizer in spring to stop new weed grasses from popping up. If you apply a spring pre-emergent, you can’t plant desirable grass seed until fall. Using a pre-emergent may be the easiest thing to do if your want to maintain and improve the lawn you have.
More information is available here:
https://apps.extension.umn.edu/garden/diagnose/weed/grass/barnyardgrass.html
Good luck!