Persian Speedwell

About

Persian speedwell is a low, hairy, sprawling weed with small sky-blue flowers that shows up in thin lawns and beds in spring. It tolerates many herbicides, so thick turf is the best defense.

Also called birdeye speedwell, bird's-eye speedwell, common field speedwell, large field speedwell, winter speedwell

How to identify it

Look for

Leaves are small, rounded and coarsely toothed, paired low on the stem and alternate higher up, and the whole plant is hairy. Single light-blue flowers with dark stripes and a white center sit on long, slender stalks from the leaf joints. Seed pods are flat and heart-shaped.

Look-alikes

Corn speedwell has flowers on very short stalks; ivyleaf speedwell has thicker, less toothed leaves; thymeleaf speedwell is nearly hairless.

Where it grows

Thin lawns, bed edges, sidewalks and gardens with moist soil, in sun or part shade.

When

Seeds sprout in fall or winter; it blooms from late winter through spring and fades in summer heat.

How it spreads

By seed; stems can also root at the joints.

Most common in

What to do, gentlest first

Start at the top. Weed killers are a last step; always read and follow the label.

1. Keep turf dense Prevent

   Fertilize, mow and water to keep a thick lawn with a grass suited to your site.

2. Hoe or pull in spring By hand

   Hoe beds or pull plants before they drop seed in spring.

3. Mulch beds Barrier

   Keep 2 to 3 inches of mulch on beds going into fall.

4. Vinegar on young plants Organic spray

   Horticultural vinegar works best on small seedlings.

   Strong vinegar (over about 11% acetic acid) can burn skin and eyes, so wear gloves and eye protection. It browns any leaves it touches, grass included.

5. Pre-emergent or labeled spot spray Conventional spray

   A prodiamine pre-emergent in fall blocks seedlings. For plants already up, choose a lawn broadleaf product whose label lists speedwell, such as ones with triclopyr, carfentrazone or sulfentrazone.

   Speedwells shrug off many herbicides, so check the label. Read and follow the label. Many lawn weed killers also harm vegetables, flowers and shrubs, so don't let spray drift into beds, and keep dicamba products off the root zones of trees and shrubs.

Uses, wildlife and pets

Pets

Not listed by the ASPCA.