The two common grassy weeds I see in my lawn are poa annua (annual bluegrass) and poa trivialis (rough bluegrass). You can see poa trivialis as the fast growing light green grass in the picture above. The leaves are broad and tapering into a sheath, and the stems feel rough.
As Benjamin Franklin said, an ounce of prevention is worth a pound of cure. I use the pre-emergent Prodiamine to prevent this rough bluegrass and other grassy weeds from growing. It’s cheaper to mix and spray, but you can also spread it granular form. You can check out my YouTube video for a how-to on mixing and spraying.
The best time to apply is when the soil temperature hits 55 degrees. This usually occurs after the air temps stay in the 60s for a few days. You can use a soil thermometer as I demonstrate in the video. There are also signs around you – the yellow forsythia blooms and the robins are hopping around your yard. Where I live in Pennsylvania, these soil temps occur around mid-April.
I apply with a 4 gallon Chapin battery powered sprayer. Make sure to wear eye protection when mixing, and wear pants when applying so you don’t get any chemical on your skin.
In a future article I’ll talk about how to prevent the broadleaf weeds like crabrass.