What is creeping speedwell?

Creeping speedwell identification is easiest in spring, when this low perennial covers patches of lawn in small, pale blue flowers. Also called slender speedwell, it comes from Turkey and the Caucasus and was sold as a rock-garden groundcover before it escaped into lawns.

The odd thing about creeping speedwell is that it almost never makes viable seed here. It spreads by its thin, creeping stems instead. Every time a mower chops those stems, the pieces can root wherever they land, so the patch quietly gets bigger mowing by mowing.

It isn’t dangerous and it won’t hurt your lawn’s soil. The problem is that it slowly crowds out grass in the areas where turf is already struggling, leaving you with a mat that looks fine in May and patchy the rest of the year.

Creeping speedwell identification: key features

• Leaves: tiny, about a quarter inch across, roundish or kidney-shaped with blunt, scalloped edges, mostly in opposite pairs.
• Stems: thread-thin, creeping along the soil and rooting as they go, forming a low, dense mat.
• Flowers: pale blue to lilac with darker lines and a white throat, four petals with one slightly smaller. Each flower stands alone on a very long, thin stalk that holds it above the leaves.
• Season: blooms mostly April through June, then fades into the turf as a green mat.

That long flower stalk is the giveaway. Most other lawn speedwells have short-stalked flowers tucked down in the leaves.

Where creeping speedwell grows in Pennsylvania

Creeping speedwell prefers cool, moist soil and handles shade well. In central PA it’s common in lawns on the north side of a house, under trees, near downspouts and along beds that get watered often. Low, damp lawns along the river valleys suit it nicely.

A lot of infestations start from a garden bed. Someone planted it years ago as a groundcover, and the mower carried it into the grass from there. It also hitches rides on mower decks from lawn to lawn.

It doesn’t do well in hot, dry, sunny turf. If you see it thriving in one corner of the yard and missing from the sunny front lawn, that pattern tells you a lot about what the grass in that corner needs: more light, better drainage or a better-adapted grass type.

Creeping speedwell look-alikes

Several speedwells show up in PA lawns, and getting the right one matters because the annual types are much easier to handle.

• Corn speedwell is a small upright annual with tiny blue flowers tucked tight against the leaves.
• Ivyleaf speedwell is a winter annual with hairy, lobed leaves like miniature ivy, and it’s gone by early summer.
• Creeping Charlie also forms a creeping mat in shady lawns, but it has square stems, larger leaves, a strong minty smell and purple, funnel-shaped flowers.

How to get rid of creeping speedwell

Hand and mechanical. Hand pulling is frustrating because the stems break and every piece left behind can root. For small patches, the best approach is to cut out the whole mat with a flat spade, a bit wider than the patch, remove all the stems, and then fill and reseed the spot. Bag clippings from infested areas in spring so you’re not spreading fragments.

Cultural. Creeping speedwell takes advantage of thin, damp, shaded turf:

• Mow at 3 to 3.5 inches so the grass shades the mat.
• Water deeply and less often, and fix spots that stay soggy.
• Overseed thin, shady areas in early fall with a shade-tolerant grass such as fine fescue.
• Clean the mower deck after cutting an infested patch.

Chemical. Many common three-way broadleaf lawn products don’t control creeping speedwell well. University turf programs, such as Cornell’s turf weed guide, list active ingredients like quinclorac and fluroxypyr for this weed. Treat when it’s actively growing in spring and plan on a follow-up in early fall, since one pass rarely finishes it. Read and follow the label (the label is the law), and make sure the product is labeled for your type of lawn grass and for any newly seeded areas. In Pennsylvania, applying herbicide for hire requires a PA Dept. of Agriculture pesticide applicator certification, so for a full-lawn program, hire a licensed lawn-care company.

Keeping creeping speedwell from coming back

Since it doesn’t spread much by seed, creeping speedwell mostly comes back from bits you missed or bits the mower moved. Watch the edges of treated or dug areas for a full season and spot-dig any new mats right away.

Don’t plant speedwell groundcovers next to the lawn. A clean bed edge with a strip of mulch also helps keep creeping stems from wandering into the grass. Over time, thick, healthy turf in the shady corners is what keeps it out.

If the shady, damp area where speedwell keeps winning is really a spot where grass will never thrive, converting it to a mulched planting bed can be the smarter long-term fix.

Questions we get about creeping speedwell

Similar weeds

Corn SpeedwellVeronica arvensisIvyleaf SpeedwellVeronica hederifoliaCreeping Charlie (Ground Ivy)Glechoma hederacea