How to Kill Trefoil in Lawns


Controlling trefoil in your lawn can be challenging, but with the right approach, it is certainly achievable. Trefoil, particularly lesser trefoil, is a common weed that can form dense patches and compete with grass for space and nutrients. Without proper intervention, it can take over your well-tended lawn. By correctly identifying the weed and understanding why it thrives, you can tailor your control methods effectively to target this persistent invader.

Mechanical removal or the use of herbicides can be effective against trefoil, but selecting the appropriate method depends on the extent of the infestation. Small patches may be dealt with manually, while larger areas might require the precision of selective herbicides designed to target trefoil without harming the grass. Moreover, through cultural practices such as proper mowing, fertilisation, and watering, you can promote a dense and healthy lawn that resists weed invasion, providing long-term weed control and maintaining the aesthetic appeal of your green space.

Things to consider:

  • Accurate identification of trefoil is crucial for effective control.
  • A combination of cultural, mechanical, and herbicidal methods may be required.
  • Post-treatment lawn care is essential to prevent weed recurrence.

Identifying Trefoil in Your Lawn

Before attempting to control trefoil in your lawn, it’s essential to accurately identify the species present. Recognising the distinct characteristics can inform the best management approach.

Characteristics of Trefoil Species

Trefoils, part of the Trifolium genus, can be identified by their leaf structure and flowering habits. Each leaf consists of three leaflets – hence the name “trefoil,” which means “three-leaved.” In your lawn, clover or trefoil species may exhibit either white or yellow flowers. The flowers of Trifolium repens, commonly known as white clover, typically have a white to pink hue and can be distinguished by the characteristic white crescent shape on each leaflet. On the other hand, Trifolium dubium, often known as lesser trefoil or yellow suckling clover, has smaller, yellow flowers and is a common annual weed found in lawns.

Common Trefoil Varieties

Among common varieties, lesser trefoil, or yellow suckling clover, is a significant weed in lawns. This plant has the ability to fix nitrogen, similar to its relatives in the pea family. It tends to blend in with your lawn due to its low growth habit, which can make it tricky to spot until it forms dense patches.

White clover (Trifolium repens) is another frequent lawn interloper, recognisable by its white flowers and the green crescent shapes on its leaflets. It’s more tolerant of mowing and can spread aggressively, causing more prominent patches that are easier to identify.

Black medic (Medicago lupulina), often confused with trefoils, has a similar appearance with its trifoliate leaves but can be identified by its black seed pods and yellow flowers.

Bird’s foot trefoil (Lotus corniculatus), not typically a lawn weed, may still be found in less maintained areas. It’s easily recognisable by its bright yellow flowers which are shaped like a bird’s foot.

By understanding the different characteristics and appearances of these trefoil species, you can target the appropriate variety when planning your weed control strategy.

Cultural Practices for Healthy Lawns

Implementing sound cultural practices is integral to maintaining a healthy lawn that can resist pests like trefoil. These practices promote vigorous grass growth, which naturally diminishes the opportunity for weeds to establish.

Effective Mowing Strategies

To ensure your lawn remains in top condition, adjust your mower blades to the correct height. In spring and summer, keep the grass at a height of 2.5 to 4 inches to encourage deeper root growth and shade out weed seedlings. Mow regularly, but never remove more than one-third of the grass blade length at a time to prevent stress and maintain grass health.

Maintaining Adequate Nitrogen Levels

Your lawn’s nitrogen requirement is pivotal to its greenness and growth rate. Aim to provide between 2 to 4 pounds of nitrogen per 1,000 square feet annually, split over several applications. In spring, apply a slow-release nitrogen fertiliser to support consistent growth. For organic lawn care, consider using compost as a natural fertiliser to improve soil health and structure.

Water Management

Water deeply but infrequently to encourage a hardy root system. Aim for about 1-1.5 inches of water per week, either through rainfall or irrigation. Early morning watering reduces evaporation and allows the grass to dry before nightfall, minimising the risk of lawn diseases. During prolonged dry spells, aeration can help water penetration and improve the efficiency of irrigation.

Mechanical and Organic Control Methods

In managing trefoil and other weeds in your lawn, mechanical and organic techniques offer environmentally friendly solutions that can effectively curb the growth and spread of unwanted plants.

Hand Removal Techniques

Using a hand fork or garden rake, you can physically remove trefoils from your lawn. Gently use the fork to loosen the roots around the plant, making it easier to dig out the entire root system. It’s crucial to remove the roots to prevent regrowth. For larger lawns, rake the area first to bring the trefoil into an upright position, ensuring that the mower captures more of the plant. Regular mowing at a high setting can help prevent clover and trefoils from seeding, reducing their presence over time.

Organic Alternatives to Chemicals

Turning to organic methods, you can create a more hostile environment for weeds without resorting to harsh chemicals. Improve soil fertility to prevent clover, as trefoil often indicates a nutrient-deficient soil. Boost your lawn’s health with organic fertilisers and well-scheduled watering to promote resilient grass that resists weed invasion. Disease management is also critical; maintaining a robust lawn through good cultural practices can naturally suppress weed problems. Organic herbicides containing naturally derived substances can target trefoil without harming nearby plants. To ensure optimal weed control, apply these treatments when weeds are actively growing and fully absorb the product.

Chemical Control of Trefoil Weeds

When tackling trefoil weeds in your lawn, using the right chemical solutions and applying them correctly is crucial for effective weed control without causing harm to your grass.

Selecting Effective Herbicides

To control trefoil effectively, look for herbicides that contain active ingredients known for targeting weeds in the clover family. A selective weedkiller is necessary to ensure that only the trefoil is eradicated, leaving your grass unharmed. The most successful products often include:

  • Mecoprop-P: Efficient in combating a wide range of broadleaf weeds, including various trefoils.
  • Fluroxypyr: Works well in conjunction with other herbicides, enhancing their weed control spectrum.
  • Dicamba: Often paired with Mecoprop-P for a synergistic effect.
  • MCPA: Another effective ingredient, particularly when mixed with the aforementioned chemicals.

Products like Weedol Lawn Weedkiller, Resolva Lawn Weed Killer, and those containing 2,4-D or Clopyralid are tailored for such specific weed targeting.

Application Tips for Optimal Results

Applying your chosen herbicide requires careful attention to achieve the desired results:

  1. Timing: Apply herbicides when trefoil is actively growing, typically in the spring or early summer.
  2. Weather Conditions: Dry, calm, and overcast days are best for application to avoid drift and maximise absorption.
  3. Equipment: Use a sprayer that gives you control over application to target weeds precisely and uniform coverage.
  4. Concentration: Follow the product’s instructions for dilution rates — improper concentrations can harm your lawn or be ineffective against trefoils.
  5. Reapplication: Some trefoils may require more than one application for complete eradication — check the instructions for guidance on reapplication intervals.

By carefully selecting a selective herbicide with the right chemicals and following the application tips, you can rid your lawn of trefoil weeds effectively.

Maintaining Your Lawn Post-Treatment

After treating your lawn to remove trefoil, it is crucial to maintain vigilance and promote a healthy lawn environment to prevent the weed from reestablishing itself. Here are specific steps to monitor for reappearance and encourage robust turf growth.

Monitoring for Trefoil Reappearance

Regularly inspect your lawn for early signs of trefoil, especially during its common self-seeding periods. If you spot new growth, immediately remove it by hand or treat it with lesser trefoil control measures to interrupt its life cycle. Stopping the spread of seeds is key to preventing future infestations.

  • Spring and Summer: Peak seasons for trefoil seed germination.
  • Post-Mowing: Look for trefoil growth, as mowing can spread seeds.

Fostering a Resilient Turf

  1. Apply appropriate lawn feed: Your lawn needs balanced nutrition. Use a feed rich in nitrogen to encourage lush growth that can outcompete weeds.
  2. Address soil amendments: Apply lime if your soil is acidic or other amendments to correct nutrient deficiencies.
  3. Manage moss: It can indicate poor lawn health, which you must address to prevent trefoil and other lawn weeds.
  4. Create drought-resistant conditions: Over-seed with drought-tolerant grass species and ensure your lawn has free-draining soils to reduce trefoil’s chance of returning.
  5. When establishing new lawns, use high-quality seed blends that can establish quickly and crowd out potential weeds like trefoil.
  • Remember, prevention is your first line of defence; a thick, healthy lawn seldom allows trefoil to take hold.
  • Repeat these steps regularly to maintain a trefoil-free lawn.

Supporting Biodiversity and Eco-Friendly Practices

Cultivating a lawn that supports biodiversity with eco-friendly practices is not just about maintaining appearances. It’s about considering the complex role that even common plants like clover play in local ecosystems and finding a balance that respects both flora and fauna.

The Role of Clover in Ecosystems

Birds-foot trefoil, part of the clover family, is a valuable plant in your garden. It boasts yellow, slipper-like flowers that support bees and other pollinators. Its leaflets participate in an essential process called nitrogen fixation—converting atmospheric nitrogen into a form usable by other plants, thus enriching the soil.

Balancing Weed Control and Wildlife

While it’s understandable to strive for a weed-free lawn, remember that what’s often perceived as weeds, such as clover, can be crucial. These plants offer habitat and food for beneficial insects and birds. When managing your garden, aim for eco-friendly practices that promote biodiversity. Avoid harsh chemicals; instead, encourage plants that compete with the less desired species by using natural methods to manage your lawn. This mindful approach supports a diverse range of wildlife while keeping your garden healthy and vibrant.

Frequently Asked Questions

Trefoil weeds like white clover and bird’s-foot trefoil can be persistent in lawns, but with the right approach, you can remove them effectively without damaging your grass. Here are some commonly asked questions to guide you through the process.

What methods are effective for removing white clover without harming the surrounding grass?

Applying a selective herbicide designed to target clover will eliminate these weeds without damaging your lawn. Proper lawn maintenance, such as adequate fertilisation and mowing, can also reduce clover growth by promoting healthy grass that outcompetes these weeds.

What is the most suitable herbicide for managing bird’s-foot trefoil in lawns?

For the control of bird’s-foot trefoil, look for a selective herbicide containing active ingredients such as fluroxypyr or clopyralid. These herbicides are specifically formulated to target broadleaf weeds while sparing the grass.

How can I manually remove clover from my lawn effectively?

Manually removing clover can be done by using a hand weeding tool to pull the plants out, roots and all, ensuring they are less likely to grow back. Regular manual removal can be effective, especially in smaller areas.

Why does my lawn have a high incidence of clover and how can I prevent it?

Your lawn may have a high incidence of clover if the soil is low in nitrogen or if the area is frequently dry. Improving soil fertility and ensuring consistent watering can help prevent clover from becoming a problem.

Can I control clover in my lawn using a natural or organic approach?

Yes, you can use natural or organic methods such as corn gluten meal as a pre-emergent weed suppressant or apply an organic fertiliser to enhance the nitrogen content in the soil, which discourages clover growth. Regular lawn care practices also contribute to organic control.

Are there selective weed killers available in the UK that target clover but spare the grass?

In the UK, there are several selective weed killers that target clover effectively while leaving grass unharmed. Look for products with labels indicating efficacy against clover or trefoil and follow the instructions carefully for the best results.

About the author 


Hey there, I am founder and editor in chief here at Good Grow. I guess I've always known I was going to be a gardener. I'm on a mission to share my UK based weed control & lawn care tips with you all. If you have any queries please post in the comments below.

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