Maintaining a lawn that includes clover, often for its nitrogen-fixing benefits and resilience, requires a precise approach to weed control. The goal is to eliminate undesirable broadleaf weeds without harming the desirable clover, which is itself a broadleaf plant. This specific challenge is met by using a selective herbicide. These chemicals are formulated to target certain plant groups while leaving others unharmed, making the choice of active ingredient paramount for success. Finding the right product depends entirely on identifying the specific weeds you need to control.
How Selective Herbicides Work
Selective herbicides function by exploiting the fundamental biological differences between plant types. In lawn care, these chemicals often target broadleaf plants (dicots) while sparing grasses (monocots), but clover is also a dicot. The most common broadleaf herbicides are synthetic auxins, which mimic natural growth hormones. When applied to susceptible weeds, these chemicals cause uncontrolled, rapid cell growth, leading to stem twisting and eventual death.
The selectivity that spares clover relies on its metabolic pathways. Clover, a legume, can process and metabolize certain herbicide compounds more quickly and effectively than target weeds. This detoxification prevents the chemical from accumulating to toxic levels within the clover’s tissues. The difference between a clover-safe and a clover-killing herbicide is often a minor alteration in the chemical structure that changes how the plant’s enzymes interact with the compound.
Active Ingredients That Spare Clover
The most reliable active ingredient for controlling broadleaf weeds while preserving established clover is 2,4-DB (2,4-dichlorophenoxybutyric acid). The “DB” is a structural modification of the common 2,4-D herbicide, which is highly effective at killing clover. This change allows the clover to metabolize the chemical into an inactive form before it causes cellular disruption. Seedling clover must already have its third trifoliolate leaf developed to safely metabolize this chemical.
Other specialized chemistries are also used. The active ingredients Imazamox and Imazethapyr, for example, are effective post-emergence options for established clover. These require application when the plant has at least two to three trifoliolate leaves. A newer generation of herbicides, like Florpyrauxifen-benzyl, offers a wider spectrum of control with a high degree of safety for clover.
Many common “three-way” broadleaf herbicides contain a combination of 2,4-D, Dicamba, and Mecoprop (MCPP), all of which will severely injure or kill clover. Therefore, carefully reading the label for 2,4-DB or other explicitly clover-safe ingredients is necessary. The concentration and formulation are often the determining factors for safety, even with a generally safer compound, and products containing Triclopyr should be avoided entirely.
Weeds Controlled by Clover-Safe Products
Clover-safe herbicides target a wide range of common broadleaf invaders that compete with turfgrass and legumes. Broadleaf weeds are susceptible to treatments containing 2,4-DB, which works because these weeds lack the metabolic mechanism to deactivate the synthetic auxin. The goal is to achieve selective control by leveraging the biological tolerance of the clover. Common susceptible weeds include:
- Dandelions
- Plantain
- Chickweed
- Dock
For grassy weeds, which are not controlled by broadleaf herbicides, a different approach is necessary. Chemicals such as Clethodim are highly effective at eliminating annual and perennial grasses, including crabgrass, while remaining safe for clover. Clethodim works because it targets an enzyme found only in grasses, leaving both broadleaf weeds and clover unharmed. Since no single product controls every weed type, a combination of targeted treatments may be necessary depending on the infestation.
Essential Application Strategies
Application timing is crucial for maximizing weed control while protecting the clover. Herbicides are most effective when target weeds are actively growing and not stressed by drought or high temperatures. Many clover-safe products recommend avoiding application when temperatures exceed 85 degrees Fahrenheit, as heat can increase the absorption rate and lead to unintentional clover damage. Fall applications are often the most effective because weeds are moving nutrients to their roots for winter, which helps translocate the herbicide throughout the plant.
Precise application is necessary to prevent injury to the clover. Using a sprayer for spot treatments on individual weed patches is a safer method than a broadcast application over the entire lawn. Following the product label’s specified rate is essential, as even clover-safe herbicides can cause damage if applied at higher-than-recommended concentrations. It is recommended to wait at least one to two days before or after applying the chemical to mow the lawn, allowing maximum leaf surface area for herbicide absorption.