Annual bluegrass in a lawn; remnants of the desired turfgrass are dark green.
Photo: Miri Talabac, University of Maryland Extension
Updated: October 23, 2026
Annual bluegrass (Poa annua) is a common weedy grass found in Maryland lawns. It is most noticeable in early spring as it reaches mature size and begins to flower and go to seed. It can be accidentally introduced to lawns when overseeding using a mixture contaminated with annual bluegrass seeds.
Despite its prominence, this is not a weed to be concerned about in a home lawn. However, its presence or abundance can be an indication of soil that is too compacted and constantly moist for turfgrass to thrive.
Annual bluegrass tends to die out when the weather becomes warm closer to summer. Patches of dead annual bluegrass creates bare spots in a lawn that should be reseeded in early fall to guard against erosion and additional weed colonization.
Life cycle and reproduction
Annual bluegrass is a winter annual: seeds germinate starting in autumn, the plants overwinter, and mature in spring, when they flower and ripen seeds before dying by summer. Annual plants have a one-year life cycle. Some seed may germinate in winter or spring, but most sprout in autumn.
Annual bluegrass spreads by seed.
Growth habit
A bunch-type grass, this species grows in discrete clumps that do not produce spreading runners. (In rare cases, some forms might produce short stolons.) It matures less than 1 foot tall — often it's only a few inches high — and tolerates low mowing well.
Conditions that favor growth
Annual bluegrass favors cool, moist conditions, and it is very tolerant of compacted soil. It spreads quickly in areas of sparse turfgrass and along lawn edges (such as driveways and sidewalks) which tend to have compacted soil from people stepping off of the pavement. It can also pop up in mulched or unmulched garden beds.
Identification
- Growth habit: clumping; no rhizomes or stolons (typically)
- Pale-colored, short, stout seed heads produced primarily in spring
- Leaf blades have a keeled (boat-shaped) tip, with no hairs and no auricles
- Ligule: membranous
- Vernation: folded
Annual bluegrass management in lawns
General lawn care practices that discourage weeds
Maintain healthy, dense turf that can compete with weeds and prevent weed germination and establishment. Avoid overwatering and applying too much nitrogen fertilizer. Core aerate in early autumn to reduce soil compaction.
Lawn care and maintenance
Mechanical management
Remove annual bluegrass clumps (including the roots) by hand or with a manual weeding tool. Doing this when the soil is moist makes the task easier. Pulling up or digging out individual plants is a viable option at the beginning of an infestation (when the plants are not yet abundant) and for young annual bluegrass plants.
Manage Weeds Without Chemicals
Chemical management
Herbicide use should always be a last resort when managing weeds. Check for any local pesticide restrictions before buying and applying a product. For example, the Montgomery County pesticide law does not allow most synthetic pesticides (which includes herbicides) to be used on lawns. The active ingredient glyphosate is also prohibited on lawns in Baltimore City.
Learn about herbicide classifications and terminology:
Herbicide Options for Managing Common Lawn Weeds
Pre-emergent
Annual bluegrass seeds primarily germinate in early autumn (September). To suppress germination, apply a pre-emergent lawn herbicide around mid-August or early September before the seeds germinate. In that situation, you will not be able to sow turfgrass seed, which would be similarly affected by the herbicide. Some crabgrass pre-emergent products are also labeled for Poa annua, so check the label. Research shows that annual bluegrass is becoming resistant to the pre-emergent product Barricade (active ingredient prodiamine). Check the labels of Dimension (active ingredient dithiopyr) and Halts (active ingredient pendimethalin) for product-specific information on Poa annua control.
Post-emergent
Spring management options of annual bluegrass plants already growing are limited since there are very few selective herbicides available for home lawn use. An application of non-selective herbicide may work, but would also damage any turfgrass exposed to the herbicide.
