Weed and Feed is a combined lawn care product that delivers two distinct functions in a single application: weed control and fertilization. It allows homeowners to address unwanted plants and nourish turfgrass simultaneously. The central question revolves around the herbicide component: is it formulated to eliminate weeds that are already visible and established? The answer depends entirely on the specific type of herbicide included in the product’s formulation.
How Weed and Feed Targets Weeds
The ability of a Weed and Feed product to kill existing weeds is determined by the type of herbicide it contains, which falls into two main categories. Most commonly, these products contain a post-emergent herbicide, designed to control weeds that have already sprouted and are actively growing. These herbicides, such as 2,4-D, Dicamba, or MCPP, are selective, meaning they are formulated to target broadleaf weeds like dandelions and clover without harming the turfgrass itself when applied correctly.
The granular form of post-emergent Weed and Feed works through contact. The herbicide granules must stick to the leaves of the existing weeds so the active ingredients can be absorbed into the plant’s system. Once absorbed, the chemicals typically disrupt the weed’s growth hormones, leading to distorted growth, yellowing, and eventually the death of the plant, including the root system. This mechanism is what makes it effective against visible, established weeds.
The other type of weed control is a pre-emergent herbicide, which does not kill existing weeds but instead prevents new ones from germinating. Pre-emergent products create a chemical barrier in the soil that inhibits the sprouting process of weed seeds, such as crabgrass, before they can become visible plants. Many comprehensive Weed and Feed formulas combine both pre-emergent and post-emergent chemicals to offer immediate control of existing plants and long-term prevention of future weed growth.
The Function of the Fertilizer Component
The “Feed” portion of the product is a complete fertilizer designed to strengthen the turfgrass. Fertilizer provides the grass with essential macronutrients, commonly represented by the NPK ratio on the product label. The three main nutrients are Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen promotes deep green color and vigorous shoot growth. Phosphorus supports root development and energy transfer. Potassium strengthens the grass against environmental challenges like drought, heat, and disease.
The boost in health from the fertilizer component works hand-in-hand with the herbicide for long-term weed management. By encouraging the existing turf to grow thicker and denser, the strong grass blades crowd out available soil space. This dense canopy effectively blocks sunlight from reaching the soil, making it significantly harder for new weed seeds to germinate and establish themselves. The fertilizer component serves as a preventative measure by creating a vigorous, competitive lawn environment.
Essential Steps for Effective Application
To ensure both the weed-killing and feeding components work optimally, the application must be carefully timed and executed. For post-emergent herbicides to be effective against existing weeds, the granules must adhere to the leaf surface to be absorbed. This means the lawn should be slightly damp when applied, often achieved by applying after a morning dew or light rain.
Applying the product when weeds are young and actively growing—typically in the spring or early fall—maximizes the herbicide’s effectiveness. Temperature also plays a role, with most products performing best when daytime temperatures are between 60 and 90 degrees Fahrenheit; application should be avoided during periods of extreme heat or drought. After application, wait 24 to 48 hours before watering or mowing, allowing sufficient time for the chemicals to translocate into the weed’s system.
The product must be spread evenly across the lawn using a broadcast or drop spreader to prevent over-application, which can burn the grass, or under-application, which results in poor weed control. Reading the product label for specific spreader settings and application rates is necessary to achieve uniform coverage. The precise timing for pre-emergent action, on the other hand, is often tied to soil temperature, requiring application before weed seeds have a chance to sprout.