Lawn Guardian

How to Get Rid of Corn Speedwell

Veronica arvensis

broadleaf weedUSDA zones 3–9Active: spring, winter

Winter annual speedwell with tiny blue flowers. One of the most common lawn speedwells. Germinates in fall, blooms in spring, dies in summer.

How to identify it

Very small, hairy, triangular leaves; tiny blue 4-petaled flowers; low upright growth; heart-shaped seed capsules.

Treatment options

Cultural (prevention): Fall overseeding

Dense fall turf prevents corn speedwell germination. This winter annual germinates in fall.

When: Overseed in early fall

Organic: Hand pulling

Shallow-rooted and easy to pull. Remove in early spring.

When: Pull in early spring before seed set

Chemical: Triclopyr herbicide

More effective than 2,4-D on speedwell species.

When: Apply in fall or early spring when actively growing

Active ingredient: Triclopyr — e.g. T-Zone

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.

Stop corn speedwell at the right moment, automatically

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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Related weeds

Sources: Purdue University Turfgrass Science: Use Growing Degree Days to Better Time Your Applications · University of Missouri Extension: Cool-Season Grasses: Lawn Maintenance Calendar · University of Minnesota Extension: Pre-emergent Herbicides for Crabgrass Control in Lawns