How To Kill Creeping Bentgrass Weeds and Prevent Its Growth? - Plant Care Guide

To kill creeping bentgrass weeds and prevent its growth, identify it by its fine texture and stolon spread, then apply a targeted, selective herbicide for bentgrass in desired lawns or consider non-selective options for complete eradication followed by reseeding. Prevention involves good lawn care, proper mowing height, and pre-emergent herbicides.

What exactly is creeping bentgrass and why is it a problem in lawns?

Creeping bentgrass (Agrostis stolonifera) is a fine-bladed, cool-season turfgrass commonly found on golf courses, where its extremely low mowing tolerance creates a pristine, putting-green like surface. However, when it invades a home lawn, it quickly becomes a problematic weed due to its aggressive spreading habit, distinct appearance, and significantly different care requirements compared to most common lawn grasses like Kentucky bluegrass or tall fescue.

How can I identify creeping bentgrass in my lawn?

Identifying creeping bentgrass is the crucial first step to effective control. Look for these key characteristics:

• Extremely Fine Texture: This is the most noticeable feature. Creeping bentgrass has very fine, delicate blades that are much thinner than most common lawn grasses. It looks almost feathery compared to the surrounding turf.
• Light Green Color: It often has a distinct lighter green or yellowish-green color that stands out from the darker green of many lawn grasses. This contrast is especially noticeable.
• Dense, Mat-like Growth: It forms very dense, thick patches that can feel spongy underfoot. These patches can quickly expand.
• Stoloniferous Growth: Creeping bentgrass spreads aggressively by sending out above-ground stems called stolons. These stolons creep along the soil surface, rooting at nodes as they go, creating new plants. You can often see these stolons by carefully parting the grass in an affected area. This is how it "creeps" and rapidly invades.
• Low-Growing Habit: It thrives under very low mowing heights. If your lawn is mowed at a typical height (2-3 inches), the creeping bentgrass will often look matted down or "scalped" in patches, making it even more noticeable.
• Seedheads: In summer, it can produce small, airy, purplish-tinged seedheads, but this is less common in frequently mowed lawns.

Why is creeping bentgrass considered a difficult weed to control?

Creeping bentgrass's characteristics make it a formidable opponent for homeowners.

• Aggressive Spreader: Its stoloniferous growth allows it to rapidly colonize large areas, quickly forming large, unsightly patches. Even a small fragment of a stolon left behind can re-root and start a new patch.
• Different Cultural Requirements: This is its biggest downfall in a home lawn.
  • Mowing Height: It prefers extremely low mowing (0.5 inches or less), while most home lawns (Kentucky bluegrass, fescue, rye) thrive at 2-3 inches. Mowing a home lawn at bentgrass height stresses the desired turf. Mowing bentgrass at regular lawn height leaves it matted and scalped.
  • Fertilization: It requires very high fertility and frequent nitrogen applications, much more than a typical home lawn.
  • Watering: It needs consistent, shallow watering, while most lawns prefer deep, infrequent watering.
• Herbicide Resistance/Sensitivity:
  • Limited Selective Options: There are very few selective herbicides that can kill creeping bentgrass without also harming your desired lawn grasses. Those that do exist are often specialized and require precise application.
  • Non-Selective Necessity: Often, non-selective herbicides (which kill everything) are the only fully effective way to remove large infestations, requiring you to kill desirable grass as well and then reseed.
• Resilience: Even after treatment, its stolons can lay dormant and resprout, making persistent follow-up critical.

Due to these factors, controlling creeping bentgrass requires a targeted, patient, and often multi-faceted approach.

What are the best methods to kill creeping bentgrass weeds?

Killing creeping bentgrass effectively requires a strategic approach, as it's a persistent weed. The method you choose will depend on the size of the infestation, your tolerance for temporary damage to your lawn, and your long-term goals.

Can I manually remove creeping bentgrass?

Manual removal is a viable option for small, isolated patches but is extremely labor-intensive for larger areas.

• Effectiveness: For patches up to 1-2 feet in diameter, manual removal can be very effective, but it requires thoroughness.
• Technique:
  1. Dig Deep and Wide: Using a sharp spade or garden trowel, cut around the perimeter of the bentgrass patch.
  2. Remove Entire Mat: Dig deep enough to remove the entire stolon mat, including the roots. Because it roots at nodes along its stolons, you need to lift a significant section of soil. Aim to get at least 2-3 inches deep and extend slightly beyond the visible bentgrass patch.
  3. Inspect Thoroughly: Sift through the removed soil with your hands to ensure no stolon fragments are left behind. Even a tiny piece can re-root.
  4. Dispose Safely: Place all removed bentgrass material in a sealed bag and dispose of it. Do not compost, as it can easily re-root.
  5. Refill and Reseed: Fill the excavated area with fresh topsoil and immediately reseed with your desired lawn grass.
• Limitations: This method is impractical and creates too much disturbance for widespread infestations.

What selective herbicides can I use for creeping bentgrass?

Selective herbicides are designed to kill specific weeds without harming desirable turfgrasses. However, for creeping bentgrass, the options are limited, complex, and often require professional application.

• Professional Products: Many of the most effective selective herbicides are professional-grade and not available to homeowners, or require specialized knowledge to apply safely and effectively. These often contain active ingredients like:
  • Mesotrione: (e.g., Tenacity Herbicide) This is one of the few active ingredients that can selectively suppress or kill bentgrass in cool-season turf. It works by inhibiting a specific enzyme. It's often used with a surfactant and requires multiple applications. However, it can cause temporary whitening of desired turf.
  • Pylex Herbicide: Another professional-grade product that targets bentgrass.
• Homeowner Limitations: It is highly unlikely you will find an effective homeowner-grade selective herbicide specifically for creeping bentgrass that won't also damage your lawn. Most common broadleaf weed killers are ineffective against bentgrass (which is a grass, not a broadleaf weed). Grass-specific selective herbicides (like those containing Sethoxydim) will also kill desirable lawn grasses.
• Key Considerations for Selective Herbicides:
  • Precise Application: Even professional products require precise calibration and application to avoid harming desired turf.
  • Multiple Applications: Typically, 2-3 applications spaced weeks apart are needed.
  • Temporary Discoloration: Desirable turf might temporarily whiten or yellow.
  • Cost: These products can be expensive.
  • Surfactant: Often require the addition of a non-ionic surfactant for better absorption.
  • Read the Label: If you do manage to find a suitable selective herbicide, read the label meticulously for grass types, application rates, and intervals.

When should I use non-selective herbicides for bentgrass?

Non-selective herbicides kill all green plants they touch. This is often the most effective and practical solution for larger infestations of creeping bentgrass in a home lawn, but it means sacrificing your existing lawn in the treated area.

• Active Ingredient: The most common and effective non-selective herbicide is glyphosate (e.g., Roundup, Spectracide Weed & Grass Killer).
• When to Use:
  • Large, Widespread Infestations: If bentgrass patches are numerous or cover a significant portion of your lawn.
  • After Manual Attempts Fail: If manual removal proves ineffective due to deep or widespread stolons.
  • Renovation: If you're planning a complete lawn renovation, using glyphosate to clear the area before reseeding or sodding is a common approach.
• Technique:
  1. Apply to Actively Growing Bentgrass: For best results, apply glyphosate when the creeping bentgrass is actively growing, usually in spring or fall, and temperatures are above 60°F (15°C).
  2. Spot Treatment or Broadcast:
     • For localized patches, use a pump sprayer to carefully apply only to the bentgrass. Shield desirable turf with cardboard if necessary.
     • For widespread infestations, you might need to broadcast spray the entire affected area.
  3. Multiple Applications: Bentgrass is tough. You might need 2-3 applications spaced 7-14 days apart to ensure all stolons are killed. Wait until the bentgrass is completely brown and dead before proceeding.
  4. Wait Before Reseeding: After the bentgrass is dead, wait the recommended period (usually 7-14 days for most glyphosate products) before reseeding your desired lawn grass. This ensures the herbicide has completely deactivated in the soil.
• Limitations: Kills everything, requiring reseeding or resodding the treated areas. This means temporary bare spots in your lawn.

The choice between manual, selective, or non-selective methods depends on the severity of your creeping bentgrass problem and your willingness to manage potential temporary damage to your lawn.

How can I prevent creeping bentgrass from growing and returning?

Preventing creeping bentgrass from establishing or returning is often more effective and less labor-intensive than trying to kill it once it has taken over. A strong, healthy lawn is your best defense.

What are good lawn care practices to deter creeping bentgrass?

Maintaining a robust lawn that outcompetes weeds is the most sustainable prevention strategy.

• Proper Mowing Height: This is paramount. Most desirable cool-season lawn grasses (fescue, bluegrass, rye) should be mowed at a height of 2.5-3.5 inches. Creeping bentgrass cannot compete at these heights. Taller grass shades the soil, keeping it cooler and suppressing bentgrass seed germination and stolon growth.
• Deep, Infrequent Watering: Most lawns prefer deep watering (to encourage deep root growth) once or twice a week, allowing the top inch or two of soil to dry out between waterings. Creeping bentgrass prefers shallow, frequent watering, so adopting deep watering habits stresses the bentgrass.
• Proper Fertilization: Fertilize your lawn according to its specific needs, promoting strong growth of your desired turf. A soil test can guide you on nutrient requirements. Avoid excessive nitrogen, which can encourage bentgrass if it's already present.
• Good Soil Health: Improve soil structure and drainage by adding organic matter (compost). Aerate compacted lawns annually or biannually to improve air and water penetration.
• Overseeding Regularly: Periodically overseed your lawn with your desired grass varieties (e.g., Kentucky bluegrass, fescue). A dense turf leaves no room for bentgrass to establish.

Can I use pre-emergent herbicides to prevent bentgrass?

Pre-emergent herbicides create a barrier that prevents seeds from germinating. This can be an effective part of a prevention strategy.

• How it Works: Pre-emergent herbicides form a chemical barrier in the soil that inhibits the development of germinating seeds. They do not kill existing plants.
• Timing: Apply pre-emergents in early spring before soil temperatures consistently reach 50-55°F (10-13°C), which is when cool-season weeds like bentgrass begin to germinate. You might need a second application in late summer/early fall for fall germination cycles.
• Active Ingredients: Common pre-emergent active ingredients include prodiamine, dithiopyr, and pendimethalin.
• Important Considerations:
  • Do Not Apply Before Seeding: Pre-emergents will prevent all seeds from germinating, including your desired grass seeds. If you plan to reseed your lawn, do not apply a pre-emergent in the same season.
  • Not for Existing Bentgrass: Pre-emergents will not kill existing creeping bentgrass plants or their stolons; they only prevent new seeds from sprouting.
  • Read the Label: Always follow the manufacturer's instructions precisely regarding application rates, timing, and re-entry intervals.
• Selective Pre-emergents: Some specialty pre-emergents are designed to prevent specific grassy weeds, but again, always verify effectiveness against bentgrass and safety for your lawn type.

What are other preventive measures?

Beyond general lawn care and herbicides, other practices can help keep creeping bentgrass at bay.

• Clean Equipment: If you or a landscaper mow areas with bentgrass, ensure mowers and other equipment are thoroughly cleaned before moving to unaffected areas. Bentgrass stolons or seeds can easily be transferred.
• Inspect New Turf/Soil: If bringing in new sod or topsoil, inspect it carefully to ensure it's free of bentgrass stolons or seeds.
• Edging: Install physical edging (like plastic or metal borders) along sidewalks, driveways, or garden beds adjacent to suspected bentgrass areas. This can create a barrier against creeping stolons.
• Educate Yourself: Learn to quickly identify bentgrass in its early stages. The sooner you spot it, the easier it is to remove manually before it becomes established.

By combining superior lawn care practices, judicious use of pre-emergent herbicides, and diligent preventive measures, you can create a healthy, dense lawn that naturally resists the invasion and growth of creeping bentgrass weeds.