Clover, most commonly white clover (Trifolium repens), is a broadleaf weed frequently found invading turfgrass areas. While some people appreciate its green cover and nitrogen-fixing properties, others desire a uniform, clover-free lawn. Clover is a persistent plant that spreads easily by seed and creeping stems, requiring a multi-faceted approach for effective removal and long-term prevention. The strategies for eradication range from simple physical removal and organic applications to targeted chemical treatments.
Non-Chemical Removal Methods
For small, isolated patches of clover, manual removal is the most direct non-chemical method. Clover has a shallow root system, making it relatively easy to hand-pull, especially when the soil is damp after rain or watering. Ensure the entire root and any creeping stolons are removed to prevent regrowth.
Another organic approach involves applying a household spray mixture to scorch the clover leaves. A solution of one cup of white vinegar, one cup of water, and one drop of liquid dish soap can be mixed and sprayed directly onto the clover. The vinegar dries out the plant tissue, and the dish soap helps the mixture adhere to the leaves. This method is non-selective, meaning it will also damage or kill turfgrass, so careful spot treatment is necessary.
For larger, dense patches, light deprivation, or smothering, can eliminate the weeds. Covering the area with black plastic sheeting or thick layers of newspaper for several weeks will block sunlight and starve the clover. Corn gluten meal (CGM) serves as an organic pre-emergent herbicide, releasing peptides that inhibit root formation in germinating seeds. CGM also acts as a slow-release nitrogen fertilizer when applied before seeds germinate in the early spring or late summer.
Targeted Herbicide Use
When clover infestations are too widespread for manual or organic control, targeted herbicide use is often necessary. Clover is a broadleaf weed, and effective chemical control relies on selective post-emergent herbicides that kill broadleaf plants without harming turfgrass. These products often contain active ingredients like 2,4-D, MCPP (mecoprop), dicamba, or a combination of all three. These chemicals mimic natural plant growth hormones, causing the clover to grow uncontrollably and eventually die.
The timing of application is a significant factor in the success of chemical treatment. Herbicides are most effective when the clover is actively growing, which typically occurs in the spring and fall. Fall application is particularly effective because the clover is actively moving nutrients down to its root system to prepare for winter, which helps systemic herbicides translocate deeper into the plant for a more complete kill. It is also recommended to wait at least two days after mowing before applying the herbicide to ensure maximum leaf surface area for absorption.
When using any herbicide, safety precautions must be followed. Always wear the recommended personal protective equipment (PPE). Apply the product on a calm day to prevent drift onto non-target plants, and avoid application during periods of extreme heat, as this can stress the turfgrass. Read the product label to ensure the selected herbicide is safe for the specific type of turfgrass in the lawn.
Long-Term Prevention Through Lawn Health
The most effective long-term strategy for preventing clover recurrence is establishing a dense, healthy turfgrass stand that outcompetes the weed. Clover is a legume, meaning it can fix atmospheric nitrogen into the soil through a symbiotic relationship with bacteria in its root nodules. This unique ability allows it to thrive in nitrogen-deficient soil, where turfgrass struggles.
Applying a nitrogen-rich fertilizer regularly helps grass grow vigorously, creating an environment unfavorable to clover. A soil test can identify specific nutrient deficiencies and pH imbalances, which are often overlooked causes of thin turf. Clover generally prefers a soil pH between 6.0 and 7.0, and correcting an overly acidic or alkaline pH to the optimal range for the desired turfgrass will further discourage clover growth.
Adjusting the mowing height is a simple practice for prevention. Setting the mower to a height between 3 and 4 inches encourages the grass blades to grow taller and denser. This taller grass shades the soil surface, blocking the sunlight needed for clover seeds to germinate and establish. Overseeding the lawn in the fall or spring increases turf density, actively crowding out any open space for clover to colonize.