Grassy Weeds - St Augustine Lawn - Annual Bluegrass
BES-TEX WEED ID GUIDE · GRASSY WEEDS
Annual Bluegrass
Also called Poa annua · Poa annua
Common Name
Annual Bluegrass
Latin Name
Poa annua L.
Family
Poaceae
Life Cycle / Type
Annual · Grass
What Is It?
Annual bluegrass is a troublesome winter annual grass that can persist and produce unsightly seedheads in mowed turf, even at extremely low mowing heights. Like all bluegrasses, its leaves have folded vernation and a boat-shaped tip. The ligule is membranous and there is no auricle. It forms a light-colored seedhead even when mowed very low.
Leaf Shape Identification (Quick ID)
Annual Bluegrass (Poa annua)
- Leaf tip: Boat-shaped
- Leaves folded in the bud
- Ligule is membranous; no auricle
- Light green leaves with two clear lines, one on each side of the midrib
- Light-colored panicle seedhead, even at low mowing heights
One-Sentence Counter Script“If it is a light green winter grass with a boat-shaped leaf tip and white seedheads in a mowed lawn, it is annual bluegrass.”
Soil Temperature & Germination
Annual bluegrass is a winter annual. It germinates in late summer and fall as soils cool.
Below 70°F
Germination begins (AgriLife); usually September or October in Texas
About 70°F for several days
AgriLife timing for a fall pre-emergent application
Decision Question
Is the annual bluegrass visible above the soil right now?
Why This Weed Comes Back
Seedheads form even at very low mowing heights
Shallow, frequent irrigation and poor soil drainage
Excessively close mowing, compaction, and shade
Learn the Basics
A healthy, thick lawn is the best defense against weeds.