What is creeping bentgrass?

Accurate creeping bentgrass identification matters because the grass golf courses love on their greens becomes a weed in a home lawn. It’s a fine-bladed, cool-season perennial that spreads with surface runners called stolons, forming dense, puffy patches that look different from the rest of your grass.

Mowed at an inch and a half to three inches like most home lawns, it can’t stay neat. The runners pile up into a spongy mat, the patches lie over and swirl, and in hot summer weather they often turn brown or get hit by disease while the surrounding lawn stays green.

Creeping bentgrass identification: what to look for

Start by looking at the lawn from a few steps back. Bentgrass patches are usually lighter or more bluish-green than the surrounding bluegrass or fescue, and they have a fluffy, matted look, almost like a cowlick.

• Runners: Grab a handful of the patch and pull up. You’ll find long, wiry stolons lying on the soil surface and rooting at each joint.
• Leaf blades: Very narrow, around an eighth of an inch, flat and pointed, with fine ridges on top.
• Ligule: Bend a blade back where it joins the stem. Bentgrass has a tall, thin, papery collar there, and no claw-like auricles.
• Feel: Walk on it. The patch feels soft and springy, and it often has a layer of thatch underneath.

Bentgrass patches grow outward a little each year, so a spot the size of a dinner plate can become several feet across over a few seasons.

Where it grows in Pennsylvania

Creeping bentgrass loves cool, moist conditions, which central PA has plenty of. It’s often worst in low, damp areas of the yard, along downspouts, in shaded corners, and in heavier clay soils that stay wet.

Seed blends sold years ago sometimes included bentgrass, and pieces of runner can arrive on mowers, aerators and sod. Homes near golf courses tend to see more of it too. Once it’s in, it doesn’t leave on its own.

Creeping bentgrass look-alikes

The most common mix-up is with nimblewill, which also forms wiry, creeping patches. The easy difference is timing: nimblewill is a warm-season grass that turns tan in early fall and greens up late in spring, while bentgrass stays green in cool weather. Nimblewill’s leaves are also short and stubby.

Bermudagrass browns out after the first frost and has a fringe of hairs instead of a papery ligule. Rough bluegrass also likes damp shade, but its leaf tips are boat-shaped and the underside of the blade is shiny.

How to get rid of creeping bentgrass

There’s no quick fix. You can’t pull it out by hand because the runners break and regrow, and normal broadleaf weed killers don’t touch it because it’s a grass.

• Small patches: Dig out the patch and a few inches beyond the edge, removing all the runners, then fill with clean topsoil and reseed or patch with sod.
• Selective control: Mesotrione is labeled for selectively suppressing bentgrass in Kentucky bluegrass, tall fescue and perennial ryegrass lawns. It usually takes several applications spaced a couple of weeks apart, and treated patches turn white before they die. Results vary, and it’s not labeled for fine fescue lawns.
• Kill and reseed: The most reliable approach is spot-treating patches with glyphosate, which kills any grass it touches, waiting for them to brown out, then reseeding. A second treatment of any regrowth before seeding helps.

Always read and follow the product label (the label is the law), and make sure it’s labeled for your lawn type and site. Applying herbicide for hire in Pennsylvania requires a PA Department of Agriculture pesticide applicator certification, so larger jobs go to a licensed lawn-care company. Plan the work for late summer so you can reseed in the late-August to mid-September window.

Keeping it from coming back

Bentgrass thrives where the soil stays wet, so fixing soggy areas matters. Regrading low spots, redirecting downspouts or adding a French drain can make the area less inviting for bentgrass and better for your lawn grass.

Mow at three to three and a half inches, and water deeply and less often instead of a little every day. Buy quality seed, and check the label: the ‘other crop’ and weed seed lines should not list bentgrass. Clean mowers and aerators after working on an infested lawn so you don’t drag runners into clean areas.

Keep an eye on the edges of any spot you’ve treated. Bentgrass runners that survive at the margin will creep back into the new grass, so catch them in the first season while the patch is still small. A thick, healthy stand of bluegrass or tall fescue is the best long-term defense.

Questions we get about creeping bentgrass

Similar weeds

NimblewillMuhlenbergia schreberiBermudagrassCynodon dactylonTall Fescue (Clumps in Lawns)Festuca arundinacea