Weed and feed is a combination product that simplifies lawn care by delivering fertilizer to nourish the turf and herbicide to control weeds in a single application. Because it contains active chemical ingredients, correct application timing and frequency are necessary to maximize effectiveness and avoid damaging the lawn. The optimal timing depends on the specific ingredients and the seasonal life cycle of the targeted weeds.
Understanding Product Types and Timing
The herbicide component dictates the timing because herbicides are only effective under specific conditions. Products usually contain either a pre-emergent herbicide, a post-emergent herbicide, or a combination of both. Pre-emergent herbicides create a chemical barrier in the soil that prevents weed seeds, such as crabgrass, from sprouting after germination.
Pre-emergent success relies entirely on soil temperature, not the calendar date. Application must occur when the soil temperature, measured at a two-to-four-inch depth, consistently registers between 50 and 55 degrees Fahrenheit for several consecutive days. Applying it too early allows the chemical barrier to degrade before weeds sprout, while applying it too late means the weeds have already begun to germinate.
Post-emergent herbicides target existing weeds like dandelions and clover, killing them through direct contact or systemic absorption. These products require the weeds to be actively growing, which happens when air temperatures are milder. For granular post-emergent products, the foliage must be moist so the granules stick to the weed leaves for absorption, often achieved by applying it when there is morning dew or after a light watering.
Timing is also influenced by the fertilizer component. High heat can cause fertilizer salts to scorch the grass, so applying the product during the late afternoon or early evening, when temperatures are cooler, helps mitigate turf damage. The type of grass (cool-season or warm-season) also affects the schedule because fertilizer should only be applied when the turf is actively growing.
Establishing the Seasonal Application Schedule
Most residential lawns should apply weed and feed no more than two to four times per year, depending on the nitrogen concentration and the existing weed problem. A minimum waiting period of 6 to 8 weeks between applications is necessary to prevent an excessive buildup of chemicals that could harm the grass. The manufacturer’s instructions provide the most accurate interval based on the product’s specific formulation and release rate.
The first application should occur in early spring, timed specifically to soil temperatures for pre-emergent weed prevention. This targets summer annual weeds and provides the first feeding to help the lawn green up as it exits winter dormancy. Wait until the grass has been mowed at least once or twice to ensure it has fully emerged from dormancy before this initial feeding.
A second application, if needed, should be applied in late spring or early summer, primarily as a fertilizer boost or as a post-emergent treatment for broadleaf weeds. The third application is in the fall, which is important for root development and preparing the turf for winter. Fall timing is also important for applying pre-emergent treatment to control winter annual weeds that germinate when soil temperatures drop below 70 degrees Fahrenheit.
Essential Pre- and Post-Application Steps
Careful preparation ensures the product works as intended and protects your lawn. Before applying granular weed and feed, mow the lawn to its normal height two to four days prior. This ensures the granules can reach the soil surface while allowing weeds enough leaf surface to absorb the herbicide.
The grass should be damp to encourage the granular weed killer to stick to the weed foliage, often achieved by applying it when there is morning dew or after a light sprinkling. Check the weather forecast; application should occur on a sunny day when no rain is expected for at least 24 to 48 hours. This delay allows the post-emergent herbicide to be absorbed by the weeds before being washed away.
Following application, keep children and pets off the treated area until the product is thoroughly watered in and the granules have dissolved. If the product contains a post-emergent herbicide, delay watering for 24 to 48 hours to allow the active ingredients to penetrate the weeds. Products focused on pre-emergent control often require immediate watering after application to activate the chemical barrier in the soil.