Creeping bentgrass (Agrostis stolonifera) is a perennial cool-season turfgrass that thrives in cool, humid regions, often in sunny locations, though it tolerates some shade. Turf professionals recognize it for its fine texture and ability to form a dense, uniform stand. While celebrated in specialized settings, its aggressive growth habit means it frequently appears as an unwanted weed in residential lawns.
Identifying Features and Growth Habit
Creeping bentgrass has a very fine texture and typically exhibits a bright or light green color. This contrast creates noticeable patches within darker turf composed of grasses like Kentucky bluegrass or tall fescue. Its leaf blades are narrow, flat, and rolled in the bud, featuring a long, tapered, membranous ligule.
The most defining feature of this grass is its growth habit, which is primarily stoloniferous. Stolons are above-ground runners that creep along the soil surface, rooting at the nodes as they grow. This mechanism allows the plant to spread rapidly and colonize large areas, forming a dense, mat-like thatch layer above the soil line.
This aggressive lateral spread makes the grass difficult to manage once established, as it quickly outcompetes neighboring turf species. Creeping bentgrass also has a shallow root system, which contributes to its high water demand and susceptibility to drought stress.
The Dual Nature of Creeping Bentgrass
The status of Agrostis stolonifera as either a desirable turf or an aggressive weed depends on the maintenance level. In professional turf management, creeping bentgrass is valued for its ability to tolerate extremely low mowing heights. This makes it the preferred cool-season grass for golf course putting greens, tees, and bowling greens, where a smooth, fast surface is required.
Maintaining this grass at low heights requires an intensive agronomic program. This includes:
- Frequent watering, often daily.
- High levels of fertilization (3 to 5 pounds of nitrogen per 1,000 square feet annually).
- Regular aeration.
- Dethatching to manage the thick thatch layer it produces.
In a typical home lawn setting, these traits turn it into an undesirable invader. The light green color and finer texture create unsightly, patchy areas that disrupt uniformity. Home lawns cannot provide the constant, intense maintenance, such as daily mowing and frequent watering, that creeping bentgrass needs, causing patches to brown out quickly during summer heat.
Control and Removal Strategies
Removing creeping bentgrass from an existing lawn is difficult due to its tenacious stolon system. Homeowners can start with cultural controls designed to stress the bentgrass while favoring deeper-rooted lawn grasses. Raising the mower height to 2.5 to 3 inches and watering deeply but less frequently will discourage its growth, as bentgrass thrives on frequent, shallow watering and low mowing.
For chemical control, selective herbicides containing the active ingredient Mesotrione are used. Mesotrione works by inhibiting photosynthesis, causing the bentgrass to turn white before dying. Multiple applications, typically three to four applied at two-week intervals, are necessary to achieve significant control, as a single application is ineffective against the persistent stolons.
Applying Mesotrione in the fall is preferred for consistent results, though the process may need repetition over multiple seasons for complete eradication. For severe, widespread infestation, a complete lawn renovation using a non-selective herbicide like Glyphosate may be the most efficient option. This involves killing all vegetation, removing the dead grass, and then reseeding the area with desirable turfgrass.