Life Cycle and Description: Annual bluegrass (Poa annua) is a winter annual weed that emerges in early fall, persists through the winter, produces seed in early spring and then dies in late spring or early summer. Annual bluegrass reproduces by seed.
Annual bluegrass prefers shady, moist sites and invades weak, thin lawn areas, especially low spots and flower beds where standing water occurs. It mainly germinates in late summer through early fall when nighttime air temperatures drop to the mid-70s. This is usually occurs from September 15 to October 1 in the Coastal Plain and Sandhills area, and September 1 to 15 in the Piedmont and Mountain areas. Further germination occurs in early winter with warm days and cold nights.
Annual bluegrass produces a white-colored, pyramid-shaped seedhead in the spring. It dies in the summer with the onset of high temperatures and/or dry conditions.
Annual bluegrass has smooth, apple-green leaves with two clear lines, one on each side of the midrib that run down the length of the leaf blade. The edges of the leaf tip curve inward like the front of a boat.