Many homeowners strive for a lush, green lawn, but sometimes, that vision clashes with the reality of unwanted plants. While most see weeds as the enemy, clover offers numerous benefits and is often welcomed. But what happens when you want to maintain a clover-friendly lawn while eradicating unwanted grasses? Understanding selective herbicides and other strategies is key.
Understanding the Differences Between Grass and Clover
To effectively target grass while preserving clover, it’s essential to understand their fundamental differences. Grasses are monocots, meaning they have one seed leaf, parallel leaf veins, and fibrous root systems. Clover, on the other hand, is a dicot, possessing two seed leaves, net-like leaf veins, and a taproot. This difference in physiology is what allows certain herbicides to target one without harming the other.
Monocots vs. Dicots: A Crucial Distinction
The classification of plants as either monocots or dicots has significant implications for weed control. Many herbicides are designed to target specific metabolic pathways or structures present in one group but not the other. This selectivity is based on the plant’s cellular structure and growth processes.
Clover’s Beneficial Attributes
Before delving into methods of grass control, it’s worth acknowledging clover’s valuable contributions to lawn health. Clover is a nitrogen fixer, meaning it draws nitrogen from the atmosphere and converts it into a usable form for plants, naturally fertilizing the soil. It also attracts beneficial pollinators like bees and butterflies. In many cases, a clover-rich lawn can be more sustainable and environmentally friendly than a purely grass-based lawn.
Selective Herbicides: Your Best Weapon
The primary method for eliminating grass while protecting clover lies in the use of selective herbicides. These herbicides are formulated to target specific types of plants based on their biological makeup. When chosen carefully, they can effectively kill unwanted grasses without harming clover.
Post-Emergent Herbicides for Grassy Weeds
Post-emergent herbicides are applied after the weeds have already emerged from the soil. When dealing with grassy weeds in a clover-rich lawn, look for herbicides specifically labeled for grass control that are safe for use around legumes (the plant family clover belongs to).
These herbicides typically contain active ingredients like sethoxydim, clethodim, or fluazifop. Always read the product label carefully to ensure it’s safe for clover and to follow the application instructions precisely. Incorrect application can lead to unintended damage.
Pre-Emergent Herbicides: A Preventative Approach
Pre-emergent herbicides are applied to the soil before weed seeds germinate. While they are generally used to prevent all types of weeds, some pre-emergent herbicides are less effective on dicots like clover. However, caution is necessary, as some pre-emergent herbicides can still negatively impact clover establishment or growth.
Research which pre-emergent herbicides are least harmful to clover before application. Granular formulations are often easier to control and may pose less risk to existing clover. Remember that pre-emergent herbicides are most effective when applied before the target grasses begin to sprout.
Understanding Herbicide Labels and Application
Reading and understanding herbicide labels is paramount. The label contains critical information about the herbicide’s active ingredients, target weeds, application rates, safety precautions, and environmental considerations. Ignoring the label can result in damage to desirable plants, ineffective weed control, or harm to yourself and the environment.
Application is just as important as the herbicide selection. Use the correct sprayer, nozzle, and pressure. Avoid spraying on windy days to prevent drift. Apply the herbicide at the recommended rate, and don’t overapply, as this can increase the risk of damage to clover. Follow all safety precautions, including wearing appropriate protective gear.
Non-Chemical Methods: An Alternative Approach
While selective herbicides are often the most effective solution, there are also non-chemical methods that can help control grass in a clover lawn. These methods are often more labor-intensive but can be a good option for those who prefer to avoid herbicides altogether or who have only a small area to manage.
Hand Weeding: Precision at its Finest
Hand weeding is the most straightforward non-chemical method. It involves physically pulling the unwanted grasses from the soil. This method is best suited for small infestations or when dealing with individual grass plants.
To effectively hand weed, grasp the grass plant firmly at its base and pull gently but steadily. Try to remove the entire root system to prevent regrowth. After weeding, fill the hole with soil to prevent other weeds from taking root.
Solarization: Harnessing the Power of the Sun
Solarization involves covering the affected area with clear plastic sheeting to trap solar energy and heat the soil. This heat can kill weed seeds and young grass plants. While effective, solarization is not selective and will kill everything underneath the plastic, including clover.
Therefore, solarization is best used to prepare a new area for clover seeding or to eliminate grass in areas where clover is not desired. After solarization, you can reseed the area with clover or transplant clover from another part of your lawn.
Corn Gluten Meal: A Natural Pre-Emergent
Corn gluten meal is a natural pre-emergent herbicide derived from corn processing. It works by inhibiting root formation in germinating seeds. While generally considered safe for clover, corn gluten meal may also suppress clover germination if applied at high rates.
Use corn gluten meal cautiously in areas where you want clover to thrive. Apply it sparingly and only to areas where you are specifically trying to prevent grass seed germination. Monitor the clover’s growth and adjust your application rate accordingly.
Maintaining a Healthy Clover Lawn to Prevent Grass Infestation
A healthy, thriving clover lawn is naturally more resistant to grass infestations. By providing the right growing conditions for clover, you can create an environment that is less favorable to grass.
Soil Testing and Amendments: The Foundation of Success
Before making any changes to your lawn care routine, it’s essential to test your soil. A soil test will reveal the pH level, nutrient content, and other important characteristics of your soil. This information will help you determine what amendments are needed to create optimal growing conditions for clover.
Clover generally prefers slightly acidic to neutral soil (pH 6.0-7.0). If your soil is too acidic, you can add lime to raise the pH. If it’s too alkaline, you can add sulfur to lower the pH. Clover also benefits from phosphorus and potassium.
Proper Watering and Mowing Practices
Watering and mowing practices can significantly impact the health and vigor of your clover lawn. Water deeply and infrequently, allowing the soil to dry out slightly between waterings. This encourages deep root growth, making the clover more drought-tolerant and competitive.
Mow your clover lawn at a higher setting than you would a traditional grass lawn. This will help the clover to shade out grass seeds and prevent them from germinating. Avoid mowing too short, as this can stress the clover and make it more susceptible to disease and weed infestation.
Overseeding with Clover: Boosting Clover Density
Overseeding with clover is a simple and effective way to increase clover density and outcompete grass. Overseed in the spring or fall, when temperatures are mild and moisture is plentiful. Scatter clover seeds evenly over the lawn and lightly rake them into the soil. Keep the soil moist until the seeds germinate.
Regular overseeding can help maintain a thick, healthy clover lawn that is resistant to grass infestations. It also helps to replenish clover plants that may have been damaged by herbicides or other factors.
Specific Grassy Weeds and Their Control in Clover Lawns
Identifying the specific types of grassy weeds infesting your lawn is crucial for selecting the most effective control methods. Different grasses have different growth habits and sensitivities to herbicides.
Crabgrass: A Common Lawn Invader
Crabgrass is a warm-season annual grass that thrives in hot, dry conditions. It is a common lawn weed that can quickly spread and outcompete desirable grasses and clover. Post-emergent herbicides containing quinclorac are effective against crabgrass, but always test in an inconspicuous area first to ensure clover tolerance.
Pre-emergent herbicides can also prevent crabgrass from germinating. Apply a pre-emergent herbicide in the spring before crabgrass seeds begin to sprout. Choose a pre-emergent herbicide that is safe for use around clover.
Annual Bluegrass (Poa annua): A Winter Annual Weed
Annual bluegrass is a cool-season annual grass that germinates in the fall and winter. It is a common lawn weed that can be difficult to control. Selective herbicides containing ethofumesate can be used to control annual bluegrass in clover lawns.
Maintaining a healthy, dense clover lawn is the best way to prevent annual bluegrass infestations. Proper watering, mowing, and fertilization will help the clover to outcompete the annual bluegrass.
Tall Fescue: A Persistent Perennial Grass
Tall fescue is a perennial grass that can be difficult to control in clover lawns. It forms dense clumps that can smother desirable plants. Spot treating with a non-selective herbicide like glyphosate is an option, but it will also kill any clover it comes into contact with. Carefully paint the herbicide onto the tall fescue leaves, avoiding the surrounding clover.
Digging up the tall fescue clumps is another option, but it can be labor-intensive. Be sure to remove the entire root system to prevent regrowth. Overseeding with clover after removing the tall fescue can help to fill in the bare spots.
Troubleshooting Common Problems
Even with careful planning and execution, problems can arise when trying to control grass in a clover lawn. Here are some common issues and how to address them.
Herbicide Damage to Clover
If you accidentally damage your clover with an herbicide, don’t panic. In most cases, the clover will recover. Water the affected area thoroughly to help the clover recover. Avoid applying any more herbicides until the clover has fully recovered. Overseeding with clover can help to fill in any bare spots.
Ineffective Weed Control
If the herbicide you’re using isn’t working, it could be due to several factors. The weed may be resistant to the herbicide, the herbicide may not have been applied at the correct rate, or the weather conditions may have been unfavorable. Try a different herbicide with a different mode of action. Make sure to apply the herbicide at the recommended rate and under favorable weather conditions.
Clover Not Spreading
If your clover isn’t spreading as quickly as you’d like, it could be due to several factors. The soil may not be suitable for clover, the clover may not be getting enough sunlight, or the clover may be competing with other plants. Test your soil and amend it as needed. Make sure the clover is getting at least six hours of sunlight per day. Remove any weeds or other plants that are competing with the clover.
Maintaining a lawn that balances desirable clover with the control of unwanted grasses requires a thoughtful and informed approach. By understanding the differences between these plants, carefully selecting control methods, and promoting overall lawn health, you can achieve a thriving and sustainable landscape. Remember, patience and consistent effort are key to long-term success.
What makes clover resistant to herbicides that kill grass?
Clover’s resistance to many common grass-killing herbicides stems primarily from its broadleaf nature. These herbicides, often called selective grass herbicides or “grass killers,” are designed to target biochemical pathways unique to grasses. Clover, being a legume and thus a broadleaf plant, lacks these specific pathways, making it unaffected by the herbicide’s mode of action. This inherent difference in physiology is the key to clover’s survival when grass around it succumbs to herbicide application.
Furthermore, some clovers even exhibit enhanced tolerance or resistance mechanisms against certain herbicides, especially in agricultural settings where herbicide use is frequent. These mechanisms might involve the ability to metabolize the herbicide into inactive compounds, prevent the herbicide from reaching its target site within the plant, or even repair the damage caused by the herbicide more efficiently than grasses can. This adaptive response allows clover to thrive even in environments where grasses are actively being suppressed.
What are some common herbicides that kill grass but not clover?
Several herbicides are effective at controlling grass while leaving clover unharmed. These products generally fall into the category of selective grass herbicides and target specific metabolic processes found only in grasses. Common examples include herbicides containing the active ingredients sethoxydim, clethodim, and fluazifop-P-butyl. These chemicals disrupt fatty acid synthesis in grasses, ultimately leading to their demise while having minimal impact on broadleaf plants like clover.
It’s crucial to read the product label carefully before applying any herbicide. The label will clearly indicate which plants the herbicide will control and which it will not. Pay close attention to the application rates and timing recommendations to ensure effective grass control and minimize the risk of unintended damage to desirable plants. Consulting with a local agricultural extension agent or lawn care professional can also provide valuable insights and guidance.
How can I use selective herbicides to promote clover growth in my lawn?
Using selective herbicides to favor clover growth involves a two-pronged approach. First, identify and apply a selective grass herbicide according to the manufacturer’s instructions. This will eliminate unwanted grasses that compete with the clover for resources like sunlight, water, and nutrients. By reducing grass competition, you create a more favorable environment for clover to establish and spread.
Second, consider overseeding your lawn with clover seeds after the grass has been controlled. This ensures a good distribution of clover throughout the area. Choose a clover variety suitable for your climate and soil conditions. Regular watering and fertilization (with a fertilizer low in nitrogen to favor clover over grass) will further promote clover growth and help it outcompete any remaining grasses. Remember that clover thrives in slightly acidic soil, so a soil test and appropriate amendments can also be beneficial.
Are there any organic methods to kill grass without harming clover?
While selective herbicides offer a targeted approach, organic methods often require more patience and manual labor. Smothering is one option. Covering patches of grass with cardboard or thick layers of mulch will block sunlight and prevent the grass from photosynthesizing, eventually killing it. This method takes several weeks or months, but it avoids the use of chemicals. It’s important to ensure the edges are well-sealed to prevent grass from growing underneath.
Another organic approach is hand-pulling. This is most effective for small areas and requires diligent removal of grass clumps, including their roots. While time-consuming, it’s a very targeted method. You can also use a sharp garden tool, like a weeding knife, to carefully cut out grass clumps without disturbing the surrounding clover. Consistent effort is key for both smothering and hand-pulling to effectively manage grass without harming clover in an organic setting.
What are the potential downsides of having a clover-dominant lawn?
While clover lawns offer several benefits, there are potential downsides to consider. Clover attracts bees, which can be a concern for individuals with allergies or those who prefer a lawn less frequented by stinging insects. While clover is generally considered low-maintenance, its nitrogen-fixing properties can sometimes lead to a slight odor, especially after rainfall. Also, clover stains clothing more readily than grass, which might be a concern for families with children who play frequently on the lawn.
Another consideration is clover’s susceptibility to certain pests and diseases. While generally resistant to many common lawn problems, clover can be affected by issues like clover mites or fungal diseases. Furthermore, clover may not be as durable as some grass varieties when subjected to heavy foot traffic. Areas that experience frequent use might become patchy or require reseeding more often than grass lawns. Therefore, carefully weigh these potential drawbacks before transitioning to a clover-dominant lawn.
How does clover benefit my lawn and the environment?
Clover offers numerous benefits for both your lawn and the environment. As a legume, clover naturally fixes nitrogen from the atmosphere into the soil, reducing the need for synthetic nitrogen fertilizers. This not only saves you money but also minimizes the risk of nitrogen runoff, which can pollute waterways. Clover also improves soil structure and aeration, contributing to healthier soil overall.
Furthermore, clover is an excellent pollinator attractant, providing a valuable food source for bees and other beneficial insects. It’s also a drought-tolerant plant, often requiring less watering than traditional grass lawns, which conserves water resources. Clover typically stays green for longer periods throughout the year compared to many grasses, offering a more visually appealing lawn with less effort. It’s a sustainable and environmentally friendly alternative or addition to traditional lawns.
What should I do if I accidentally kill clover while trying to control grass?
Accidental clover death can occur due to misapplication of herbicides or the use of non-selective herbicides. If you’ve mistakenly killed clover, the first step is to identify the cause. If it was an herbicide, thoroughly water the affected area to help dilute the chemical and encourage recovery of any surviving clover. Avoid applying any further chemicals to the area for several weeks.
To restore clover, overseeding is usually the best approach. Lightly rake the bare patches to loosen the soil, then scatter clover seeds evenly over the area. Gently compress the seeds into the soil to ensure good contact. Keep the soil consistently moist until the new clover seedlings emerge and become established. Regular watering and avoiding the use of broadleaf herbicides in the future will help maintain a healthy clover patch.