Parent Species:

Which Bentgrass You Have

The putting-green grass that shows up uninvited — fine, off-color, and puffy, in a patch that scalps brown every time you mow.

Is Which Bentgrass You Have Right For Your Yard?

Best For:

Anyone watching a fine, soft, off-color patch spread through a cool-season lawn, most often in the Northeast, the Upper Midwest, or the Pacific Northwest. Especially relevant if that patch scalps brown after mowing and is the first spot to go tan in a dry stretch.

Tradeoff:

It only looks good mowed under half an inch, nearly every day, with a reel mower and a season-long fungicide program — at lawn height it becomes a puffy, scalped, disease-prone mat.

What It Is And How To Tell It Apart

If a fine, off-color patch is spreading through your lawn, it is almost certainly creeping bentgrass. It is the aggressive one, it is the one that rides along in cheap seed, and it is the only one of the three that turns up as a lawn invader across most of the country. Confirm it is bentgrass at all using the checks on the main bentgrass page — rolled shoot, tall membranous ligule, no auricles, dull leaf underside. Then use the table to pin down which species you have.

Species How you’d know it Where it turns up What it means for you
Creeping bentgrass (A. stolonifera) Blue-green to dull gray. Long runners lying on the soil surface, rooting wherever a node touches. Tall ligule, about 0.04–0.08 in — call it a sixteenth of an inch. No underground stems at all. Northeast, Upper Midwest, Pacific Northwest. The default answer if you have not identified it yet. The fastest spreader, and the one that multiplies if you rake or dethatch it.
Colonial bentgrass (A. capillaris) Lighter yellow-green and more upright, with no obvious surface runners. Short, squared-off ligule under about 0.04 in — roughly half the height of creeping bentgrass, and the most reliable way to separate the two. Mild coastal areas — the Pacific Northwest and coastal New England. Usually a leftover from old lawn or fairway seed. Grows as a tight clump rather than a mat, so it stays put. Easier to contain, no easier to spray.
Velvet bentgrass (A. canina) The finest and densest of the three, closer to carpet than lawn. Very slender runners. Long, sharply pointed ligule. Turns dark purple in cold weather. A narrow range, mainly the Northeast and older New England properties. Piles up thatch faster than the others, which changes how you treat it. Also the most shade-tolerant, so it reaches further under trees.

How It Got Here

Nobody plants bentgrass in a lawn on purpose, so the species you have is a decent clue to how it arrived.

Creeping bentgrass arrives in a seed bag. Its seed is tiny and produced in huge numbers, so it rides along as a contaminant in cheap, uncertified bluegrass and fescue mixes — extension weed specialists name this the single most common route into a home lawn. After that it travels on mower decks as chopped runner fragments, moves in with bargain sod or topsoil, and creeps across a property line from a golf course or an older neighboring yard. Often it sits unnoticed for years and only explodes into visible patches once stress or injury thins the grass around it and hands it the opening.

Colonial and velvet are usually inherited, not imported. Both were once planted deliberately — colonial for coastal lawns and fairways, velvet as a component of the South German bentgrass seed mixes sold in the early 1900s. If you have either one, the odds are strong it came with the property rather than with anything you bought.

What To Do About It

The plan is the same for all three. No herbicide kills bentgrass and spares your lawn, so it is either a glyphosate spot-treatment and reseed, or a full fall mesotrione program — both are laid out on the main bentgrass page, including the warning that mesotrione is lethal to fine fescue. What the species changes is your margin for error.

  • Spray past the edge. Creeping and velvet both send runners out unseen beneath healthy grass, so treat at least a foot past the visible patch. Colonial stays closer to its own edge because it clumps, but a buffer still pays.
  • Do not rake first. Every runner fragment can root. Dethatching, slicing, or tilling a live creeping or velvet patch turns one patch into a dozen scattered across clean turf. Wait until it is straw-brown and dead. Colonial is the lower-risk one here, and it is still not worth the gamble.
  • Account for thatch. Velvet builds a thatch layer faster than the other two. If you take the mesotrione route, raking out the dead bleached tissue between sprays matters more with velvet — otherwise the later applications never reach the runners underneath.

One buying note that catches people out: check the active-ingredient panel and confirm it actually says glyphosate. The “Roundup” name no longer reliably means glyphosate — several products now sold under that brand use different active ingredients that will not kill perennial grass runners. The front of the bottle does not tell you what is inside it; the ingredient panel does.

And set expectations honestly. Clearing a heavy bentgrass infestation usually takes more than one season of spot-treating and watching for return, whichever species you are dealing with.