Annual bluegrass Poa annua
IDENTIFICATION — Annual bluegrass is one of the first grassy weeds you’ll spot in early spring. The seeds sprout in late summer or fall and can continue to grow through a mild winter. The bright green tufts of grass are the most noticeable in spring or early summer. In cool regions where the soil stays moist, annual bluegrass grows all season; in hot and dry areas it usually dies by midsummer. This pest can grow 6 to 8 in. tall in flower or vegetable gardens but will be shorter in areas where you mow.
FAVORITE CONDITIONS — The roots are shallow, so annual bluegrass grows best in damp areas. That means you’ll often spot it growing in lawns, flower beds and other areas that stay moist or are irrigated. Although it prefers full sun, this weed can also grow in shade.
CONTROL — Since annual bluegrass seeds are spread by mowing, foot traffic, birds and cultivating tools, always clean your tools and mower before moving on to another area. Established plants are easy to pull or hoe out, so remove them before they go to seed.
Use at least a 2-in.-thick layer of mulch in borders and gardens to keep annual bluegrass from sprouting. In turf areas, raise the mower height to 2 1/2 to 3 in. to keep your desirable grass tall. Weed seeds are less likely to germinate if they’re kept in shade.