Poa annua
grassy weedUSDA zones 2–10Active: spring, fall, winterLight green annual grass that produces prolific seed heads even at mowing height. Thrives in cool, moist conditions and dies in summer heat, leaving yellow patches.
Lighter green than desired turf; boat-shaped leaf tips; whitish, open seed heads visible even when mowed short.
Dense, tall turf shades Poa annua and reduces germination. Avoid scalping.
When: Maintain 3+ inch height throughout growing season
Thick fall overseeding competes with Poa annua germination. Time seed to establish before Poa germinates.
When: Overseed in early fall before Poa annua germinates
Fall application as pre-emergent can reduce Poa annua germination.
When: Apply in late summer/early fall before Poa annua germinates
Fall-applied pre-emergent prevents winter/spring Poa annua establishment.
When: Apply in early fall when soil temp drops below 70F
Active ingredient: Prodiamine — e.g. Barricade
Grass safety: always match herbicides to your grass species — products safe on Kentucky bluegrass can kill St. Augustine or centipede. Lawn Guardian checks this automatically against your lawn profile.
Lawn Guardian turns this guidance into a schedule timed to your USDA zone and this week's actual weather — and adapts every time you log what you've done.
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