How to Get Rid of Crabgrass: A Comprehensive Guide for a Weed-Free Lawn

Crabgrass. The name itself might sound innocuous, perhaps even a bit quirky. But for homeowners striving for a lush, green lawn, crabgrass is nothing short of a nemesis. It starts subtly, a few oddly colored blades peeking through your otherwise pristine turf. Then, before you know it, it feels like a full-scale invasion. Crabgrass has arrived, seemingly overnight, to wage war on your yard’s immaculate (or, let’s be honest, usually immaculate-ish) appearance.

But don’t despair. Before a minor annoyance turns into a full-blown crabgrass infestation, know that you have options. Whether you prefer getting your hands dirty with weeding, resorting to chemical solutions, or enlisting professional help, crabgrass can be managed. This guide will arm you with the knowledge and strategies you need to reclaim your lawn and win the battle against this persistent weed, ensuring your yard is the envy of the neighborhood once again.

Understanding Crabgrass: Know Your Enemy

To effectively combat crabgrass, it’s crucial to understand what you’re dealing with. Crabgrass (Digitaria) is a summer annual weed, meaning it completes its life cycle in a single year, germinating in the spring and dying with the first frost. Here are some key characteristics to help you identify and understand its nature:

Habitat Preferences: Crabgrass thrives in compacted soil and areas where your existing lawn is thin or weak. This often includes high-traffic areas or spots where grass struggles to grow. You might find it popping up in your garden beds, along walkways, or throughout your lawn.
Growth Cycle: Crabgrass germination begins in early spring when soil temperatures consistently reach between 55 and 65 degrees Fahrenheit about 3 inches below the surface. This timing is critical for pre-emergent herbicide application, as we’ll discuss later. Growth is rapid in the heat of summer, slowing down as it sets seed in midsummer. It then dies off with the first frost of the fall.
Distinct Appearance: Crabgrass is easily distinguishable from most turfgrasses. It has coarse, yellow-green blades that are noticeably wider than typical lawn grass. It grows in a spreading, bunching habit, often described as resembling the arms of a crab, hence its name. This sprawling growth pattern allows it to quickly dominate thin areas of your lawn.
Prolific Reproduction: One of the biggest challenges with crabgrass is its prolific seed production. A single crabgrass plant can produce up to 150,000 seeds. These seeds are incredibly resilient and can remain dormant in the soil for as long as 30 years, waiting for the right conditions to germinate. This long dormancy period explains why crabgrass can seem to reappear year after year.
Adaptability and Resilience: Crabgrass is a tough and adaptable weed, well-suited to survive hot temperatures and dry conditions that can stress desirable lawn grasses. This resilience makes it particularly competitive in summer lawns.

Understanding these characteristics makes it clear that managing crabgrass is often an ongoing effort. Each growing season is essentially a new round in the fight. However, with the right strategies and consistent effort, you can gain the upper hand and maintain a crabgrass-resistant lawn.

Effective Methods to Get Rid of Crabgrass

Photo Credit: Richard Arthur Norton / Wikimedia Commons / CC BY 2.5

There are several effective methods to tackle crabgrass, ranging from manual removal to chemical treatments. The best approach often depends on the severity of the infestation, your personal preferences, and your commitment to lawn care.

1. Manual Weeding: The Hands-On Approach

For smaller crabgrass infestations or for homeowners who prefer a natural, chemical-free approach, manual weeding can be effective. Physically pulling crabgrass plants out by hand, roots and all, is a direct and sure way to eliminate individual plants.

When to Weed: The ideal time for hand-weeding crabgrass is in late spring or early summer, before the plants mature and produce seeds. Weeding is also significantly easier when the soil is moist and soft, ideally after a rain shower. Moist soil allows you to pull the entire plant, including the roots, more easily, minimizing the chance of regrowth.

Technique is Key: To effectively hand-weed crabgrass:

Loosen the Soil: If the soil is dry or compacted, use a hand trowel or weeding tool to loosen the soil around the base of the crabgrass plant.
Grasp the Base: Grip the crabgrass plant firmly at its base, as close to the soil line as possible.
Pull Slowly and Steadily: Pull the plant straight up, using a slow and steady motion to ensure you remove the entire root system. Avoid yanking, which can break the plant at the surface, leaving the roots behind to regrow.
Dispose Properly: Discard the pulled crabgrass plants in a trash bag or compost bin. Avoid leaving them on the lawn, as they can still potentially re-root or release seeds.

Pro Tip: Early and Often is Best: Regular weeding, especially early in the season, is crucial for managing crabgrass manually. Don’t wait until crabgrass becomes widespread. Catching and removing young plants before they have a chance to establish themselves and produce seeds will significantly reduce future infestations.

Myth Busting: Cutting Crabgrass Short: A common misconception is that mowing crabgrass short will kill it. Crabgrass is remarkably resilient and can produce seeds even when mowed very low – as short as 0.5 inches, which is much shorter than the recommended mowing height for most lawns. Cutting it short might make it less visible temporarily, but it won’t eliminate it. Focus on root removal instead.

2. Herbicide Application: Chemical Warfare for Crabgrass Control

When crabgrass infestations are widespread, or for those seeking a more efficient solution, herbicides can be a valuable tool. The herbicide aisle at your local home improvement store can be overwhelming, so understanding the different types and how they work is essential for effective crabgrass control.

Selective vs. Non-Selective Herbicides: For lawns, you’ll want to use selective herbicides. These are designed to target specific weeds, like crabgrass, without significantly harming your desirable lawn grasses. Non-selective herbicides, on the other hand, kill all vegetation they come into contact with and are not suitable for use on lawns unless you are specifically targeting a small area and are willing to reseed.

Targeting Grasses, Not Broadleaves: Crabgrass is a grassy weed, not a broadleaf weed like dandelions or clover. Therefore, you need to choose an herbicide that is specifically formulated to control grassy weeds. Broadleaf weed killers will not be effective against crabgrass.

Pre-Emergent vs. Post-Emergent Herbicides: This is a crucial distinction for crabgrass control:

Pre-Emergent Herbicides: These are applied before crabgrass seedlings emerge from the soil. They create a chemical barrier that prevents crabgrass seeds from germinating. Timing is critical for pre-emergents. They need to be applied in early spring, before soil temperatures reach the germination threshold for crabgrass (55-65°F at a 3-inch depth).
Post-Emergent Herbicides: These are applied after crabgrass has already emerged and is actively growing. They are designed to kill existing crabgrass plants. Post-emergent herbicides are useful for spot-treating crabgrass that has already appeared or for addressing infestations when pre-emergent application was missed or ineffective.

Liquid vs. Granular Herbicides: Both liquid and granular herbicide formulations can be effective.

Liquid Herbicides: Often require mixing with water and application using a sprayer. They provide good coverage but require careful calibration of the sprayer to ensure even application and avoid over-application.
Granular Herbicides: Are applied using a spreader, similar to fertilizer. Granular formulations are often easier to apply evenly for homeowners without specialized equipment.

Application Best Practices:

Read the Label Carefully: Always, always read and follow the product label instructions. Pay close attention to application rates, timing, safety precautions, and which grass types the product is safe for.
Watering After Application: Many herbicides require watering in after application to activate the product and move it into the soil. Follow label instructions for watering guidelines.
Grass Type Compatibility: Ensure the herbicide you choose is safe for your specific type of lawn grass. Some herbicides are not safe for certain grass varieties.

Pro Tip: Avoid “Weed and Feed” Products: “Weed and feed” products combine herbicides and fertilizers. While convenient, they are generally not recommended for crabgrass control. Because crabgrass is a grass, the fertilizer component in “weed and feed” can actually nourish crabgrass seedlings, inadvertently promoting their growth instead of inhibiting it. It’s generally better to apply fertilizer and weed control products separately, allowing for more targeted and effective treatment.

Preventing Crabgrass: Long-Term Lawn Health Strategies

Alt text: Core aeration being performed on a lawn with a ride-on core aerator machine, promoting healthy turf.

The most effective way to “get rid of” crabgrass in the long run is not just to eliminate existing plants, but to prevent it from taking hold in the first place. A healthy, dense lawn is your best natural defense against crabgrass and other weeds. Thick turfgrass creates shade that inhibits weed seed germination and outcompetes weed seedlings for resources. Here are key practices to promote a healthy, crabgrass-resistant lawn:

1. Cultivate a Healthy Lawn: The Foundation of Weed Prevention

Mow at the Right Height: Mowing your lawn at a higher setting (typically 2.5-3 inches or higher, depending on your grass type) is a crucial step in weed prevention. Taller grass blades shade the soil surface, reducing sunlight penetration and inhibiting weed seed germination, including crabgrass. Taller grass also develops deeper roots, making it more resilient and competitive against weeds.
Water Deeply and Infrequently: Watering deeply but less frequently encourages deep root growth in your lawn grass. Deep roots make your lawn more drought-tolerant and better able to access nutrients, further enhancing its competitiveness against shallow-rooted weeds like crabgrass. Shallow, frequent watering, on the other hand, can create moist surface conditions that favor crabgrass germination.
Overseed Regularly: Overseeding your lawn annually, especially in the fall for cool-season grasses, helps to maintain a dense turf. Overseeding fills in thin or bare patches where crabgrass is more likely to invade. Choose a grass seed blend that is appropriate for your climate and growing conditions.
Soil Aeration and Thatch Management: Compacted soil and excessive thatch (a layer of dead grass and debris on the soil surface) can weaken your lawn and create favorable conditions for crabgrass. Aerating your lawn annually, especially in high-traffic areas, helps to alleviate soil compaction and improve air, water, and nutrient penetration. Dethatching, if necessary, removes excessive thatch buildup, allowing for better turfgrass growth.
Proper Fertilization: Fertilizing your lawn appropriately provides the nutrients it needs to grow thick and healthy, further enhancing its ability to resist weed invasion. Follow a soil test-based fertilization plan to ensure you are providing the right nutrients at the right time of year for your specific grass type.

2. Corn Gluten Meal: A Natural Pre-Emergent Option

For homeowners seeking a more natural approach to pre-emergent weed control, corn gluten meal (CGM) is an option to consider. CGM is a byproduct of corn processing and acts as a natural pre-emergent herbicide.

How Corn Gluten Meal Works: CGM contains proteins that inhibit root formation in germinating seeds. When applied to your lawn in early spring, it can prevent crabgrass and certain other weed seeds from developing roots and establishing themselves. CGM also provides a mild nitrogen fertilizer boost to your lawn as it breaks down.

Application of Corn Gluten Meal:

Timing: Apply CGM in early spring, similar to synthetic pre-emergent herbicides, before soil temperatures reach the crabgrass germination threshold.
Application Rate: Corn gluten meal needs to be applied at a relatively high rate to be effective as a pre-emergent, typically around 20 pounds per 1,000 square feet.
Watering In: Water the corn gluten meal into the soil after application to activate its pre-emergent properties.

Limitations of Corn Gluten Meal: While CGM is a natural option, it is generally considered less effective and more expensive than synthetic pre-emergent herbicides. It may provide some crabgrass suppression, but may not be as reliable in preventing heavy infestations. Its effectiveness can also vary depending on weather conditions and application timing.

3. Pre-Emergent Herbicide Application: Proactive Crabgrass Prevention

Pre-emergent herbicides are often considered the most effective and economical tool for preventing crabgrass infestations. They work by creating a barrier in the soil that inhibits crabgrass seed germination.

Timing is Critical for Pre-Emergents: The key to successful pre-emergent application is timing. You need to apply pre-emergent herbicide before crabgrass seeds begin to germinate. This typically means applying it in early spring, when soil temperatures at a 3-inch depth are consistently between 50-55°F. Applying too late, after crabgrass has already germinated, will render pre-emergent herbicides ineffective.

Soil Temperature Monitoring: Monitor soil temperatures in your area to determine the optimal time for pre-emergent application. Soil temperature maps and local weather resources can provide helpful information.

Active Ingredients to Look For: When choosing a pre-emergent herbicide, look for products containing these active ingredients, which are known to be effective against crabgrass:

Dithiopyr: Provides good pre-emergent control of crabgrass and some other weeds.
Prodiamine: Another effective pre-emergent herbicide for crabgrass control, often found in granular formulations.
Oryzalin: Can be particularly effective on warm-season grasses.

Pre-Emergents and New Grass Seed: Most pre-emergent herbicides also prevent new grass seed from germinating. If you plan to overseed your lawn in the spring, avoid applying pre-emergent herbicides at the same time, as they will inhibit the germination of your new grass seed. Overseeding is best done in the fall for cool-season grasses. If spring overseeding is necessary, consider using a “siduron” based pre-emergent, which is safe for new grass seedlings (though less common for general crabgrass prevention). Always check product labels for specific instructions regarding seeding and pre-emergent application.

FAQ About Crabgrass: Common Questions Answered

What Factors Contribute to Crabgrass Growth?

Several lawn care practices and environmental conditions can inadvertently encourage crabgrass growth:

High Temperatures and Dry Conditions: Crabgrass thrives in hot, dry weather, conditions that can stress desirable lawn grasses and give crabgrass a competitive advantage.
Mowing Too Short: Mowing your lawn too short weakens the turfgrass, reduces shading of the soil, and allows more sunlight to reach crabgrass seeds, promoting germination.
Infrequent or Shallow Watering: Watering too frequently or too shallowly encourages shallow root growth in lawn grasses, making them less drought-tolerant and more susceptible to weed competition. Crabgrass, with its shallow root system, can thrive in these conditions.
Compacted Soil: Compacted soil restricts root growth for desirable grasses, creating thin areas where crabgrass can easily invade.

How Can I Get Rid of Crabgrass Without Harming My Desirable Grass?

Besides natural methods like hand-pulling and corn gluten meal, selective herbicides are designed to control crabgrass while minimizing harm to certain turfgrass types.

Selective Post-Emergent Herbicides: Active ingredients like quinclorac and foramsulfuron are known for their effectiveness against crabgrass in post-emergent applications. However, it’s crucial to choose a product that is safe for your specific lawn grass type. Always read and follow label instructions carefully.
- Quinclorac: Generally safe for Kentucky bluegrass, tall fescue, and Bermudagrass, but should not be used on bahiagrass, centipedegrass, fine fescue (unless in a blend), or St. Augustinegrass.
- Foramsulfuron: Suitable for Bermudagrass and Zoysiagrass but should not be applied to cool-season turfgrasses, St. Augustinegrass, or centipedegrass.
Promote Lawn Health: The best long-term strategy for weed control is to maintain a healthy, dense lawn. Regular aeration, overseeding, proper mowing and watering practices, and balanced fertilization will create an environment that is less favorable to crabgrass and more conducive to healthy turfgrass growth.

What’s the Quickest Way to Kill Crabgrass?

For immediate removal of established crabgrass:

Hand-pulling: For small infestations, hand-pulling is the fastest way to remove individual plants.
Selective Post-Emergent Herbicides: Applying a selective post-emergent herbicide is a quick way to kill larger infestations.
Horticultural Vinegar (for very young seedlings): A single application of horticultural vinegar can sometimes be effective on very small crabgrass seedlings, but it may not be as effective on mature plants and can also damage surrounding desirable grasses if not applied carefully.

What are Natural Ways to Prevent Crabgrass?

For homeowners who prefer to avoid synthetic herbicides, natural preventative measures include:

Maintaining a Healthy Lawn: As described earlier, a healthy, dense lawn is the most effective natural defense against crabgrass.
Corn Gluten Meal: As discussed, CGM is a natural pre-emergent herbicide option.

When to Seek Professional Lawn Care Assistance

While many homeowners can effectively manage crabgrass on their own, there are times when enlisting the help of lawn care professionals is beneficial.

Severe Infestations: If crabgrass has taken over a significant portion of your lawn (e.g., 60% or more), professional intervention may be the most efficient and effective way to restore your lawn’s health.
Time Constraints or Lack of Expertise: If you lack the time, equipment, or confidence to manage crabgrass effectively yourself, lawn care professionals have the expertise, tools, and products to address the problem efficiently.
Ongoing Weed Control Challenges: If you’ve tried DIY methods and are still struggling with persistent crabgrass issues, professionals can diagnose underlying lawn health issues and develop a comprehensive weed control and lawn care plan tailored to your specific situation.

Lawn care professionals can provide a range of services, including:

Crabgrass Identification and Assessment: Accurate identification of crabgrass and assessment of the infestation level.
Pre- and Post-Emergent Herbicide Applications: Proper application of effective herbicides at the correct timing and rates.
Lawn Health Services: Aeration, overseeding, fertilization, and other lawn care practices to promote long-term turf health and weed resistance.

By understanding crabgrass, implementing effective control and prevention strategies, and knowing when to seek professional help, you can win the battle against this persistent weed and enjoy a healthy, beautiful, crabgrass-free lawn.

Main image credit: Rasbak / Wikimedia Commons / CC by SA 3.0