White clover (Trifolium repens) is a perennial legume commonly found in managed turf areas, often signaling an imbalance in the lawn environment. With its distinctive three-leaflet structure, which frequently features a pale V-shaped watermark, the clover forms dense, low-growing mats that can create an uneven appearance in an otherwise uniform lawn. Although some homeowners value its drought tolerance and ecological benefits, white clover aggressively competes with turfgrass. The focus here is on non-destructive methods that specifically target the clover while promoting the health and density of the surrounding turfgrass.
Adjusting Lawn Care Practices to Suppress Clover
Altering routine lawn maintenance is the first step in controlling white clover, as these practices favor the grass over the weed. The simple act of increasing your mower’s cutting height provides a significant competitive advantage to the turf. Keeping the grass blades between 3 to 4 inches tall encourages dense growth, which effectively shades the low-growing clover and prevents the sunlight it needs for robust growth. Clover is naturally adapted to survive close mowing, so raising the deck forces the clover to stretch, making it vulnerable to shading and eventual decline.
Proper watering techniques also disrupt the clover’s ability to thrive by encouraging deeper turfgrass roots. Instead of frequent, light sprinklings, water the lawn deeply and infrequently, such as once a week, to soak the soil several inches down. This practice coaxes the turfgrass roots to grow deeper, making the grass more resilient to drought and better equipped to dominate the topsoil nutrient profile. Clover, with its more superficial stolons and roots, struggles to compete with a deeply established turfgrass root system.
For smaller, isolated patches of white clover, manual removal is an immediate, non-chemical solution. This technique requires careful execution, as the entire creeping stem, or stolon, must be removed to prevent regrowth. Hand-pulling is best performed when the soil is moist, such as after a rain or deep watering, which allows the shallow roots to be extracted intact. Using a specialized weeding tool for leverage can help ensure that the creeping stems, which root at various nodes, are lifted from the soil surface, preventing the clover from spreading further into the turf.
The Role of Nitrogen in Eliminating Clover
White clover is classified as a legume, possessing a unique biological mechanism that allows it to flourish where turfgrass struggles. It forms a symbiotic relationship with Rhizobium bacteria, which live in nodules on its roots and are capable of “fixing” atmospheric nitrogen gas into a plant-usable form. This internal nitrogen production gives clover a massive advantage, allowing it to thrive in nitrogen-poor soils that would otherwise stunt the growth of turfgrass. The presence of clover is often a visual indicator that the soil is deficient in nitrogen, the nutrient most critical for aggressive grass growth.
The most effective long-term strategy for eliminating clover without damaging the lawn is to fertilize the turfgrass with high-nitrogen products. When ample nitrogen is available in the soil, the turfgrass experiences a growth surge, becoming thick and dense. This sudden influx of readily available nitrogen also inhibits the clover’s ability to form its nitrogen-fixing nodules, effectively neutralizing its primary competitive advantage. The combination of the grass growing taller and the clover’s nitrogen supply being cut off allows the turf to outcompete and ultimately choke out the clover, as the weed is shaded and starved of its preferred nutrient source.
Before initiating a high-nitrogen fertilization program, conduct a soil test to determine nutrient deficiencies and pH level. This analysis helps in selecting a fertilizer with the appropriate nitrogen-to-phosphorus-to-potassium (N-P-K) ratio for the specific lawn. Fertilizers with a high nitrogen content, such as a 4-1-2 ratio, should be applied according to the specific needs of the turfgrass species, typically in the spring and fall, to maintain a consistent competitive edge. Consistent fertilization is the foundation for creating a dense, healthy turf sward that suppresses weed invasion and prevents the re-establishment of clover.
Choosing Selective Herbicides for Clover Control
For extensive infestations, selective herbicides offer a targeted method to remove clover while preserving the turfgrass. Selective herbicides are formulated to control broadleaf weeds, like clover, by mimicking plant hormones that cause uncontrolled growth in the weed, but they leave the narrow-leaf turfgrass unharmed. Look for products that contain a combination of active ingredients, such as 2,4-D, dicamba, or MCPP (mecoprop), as these provide broader and more effective control over perennial weeds like white clover.
Application timing is important, with late summer or early fall being the most opportune window for control. During this period, the clover is actively drawing nutrients down to its root system in preparation for winter, which allows the herbicide to be efficiently translocated throughout the entire plant, including the root structure. A secondary application can be made in the spring when the clover first emerges and is actively growing.
To minimize the impact on the lawn, spot treating is recommended, rather than a broadcast spray over the entire yard. Spot treating involves applying the product directly onto the clover patches, which reduces chemical use and limits exposure to non-target plants. Always adhere to the manufacturer’s label directions regarding dilution rates, application volume, and safety precautions. Avoid applying these herbicides on days when the temperature is forecast to exceed 85 to 90 degrees Fahrenheit, as high heat can cause the chemicals to volatilize, potentially damaging nearby desirable plants and stressing the turfgrass.