Weed and feed products are a popular dual-purpose solution for lawn care, combining fertilizer for grass nourishment with an herbicide for weed control. This convenience allows homeowners to complete two lawn tasks in a single application. The primary concern when using this combined product is balancing a lush lawn with avoiding damage from chemical overexposure. Following clear guidelines for application frequency ensures the product works effectively without harming the turf.
Components and Timing Considerations
The effectiveness of any weed and feed application depends on its two distinct active ingredients. The “feed” portion is a fertilizer, typically composed of nitrogen, phosphorus, and potassium, which are macronutrients designed to promote healthy grass growth and color. The “weed” portion is a selective herbicide, often containing compounds like 2,4-D or Dicamba, formulated to kill broadleaf weeds without damaging the turfgrass.
Timing is complicated because the optimal conditions for these two components often differ. Fertilizer is most effective when the turfgrass is actively growing and can readily absorb the nutrients, which occurs during moderate temperatures. The herbicide, especially a post-emergent type, must be applied when weeds are visible and actively growing so the chemical can be absorbed through the foliage. Pre-emergent herbicides, which prevent weed seeds from sprouting, must be applied very early in the season before germination, typically when soil temperatures reach about 55°F. Applying the product when the grass is dormant or stressed, such as during a hot summer drought, can make the turf susceptible to chemical burn from the fertilizer salts.
Recommended Application Frequency
The most important rule for determining application frequency is to consult the specific product label, which mandates the waiting period based on the concentration of active ingredients. Although product formulations vary, a general rule is to allow a minimum of 6 to 8 weeks between applications. This interval is necessary to prevent the buildup of herbicides in the soil and to manage the amount of nitrogen applied to the lawn.
Most manufacturers recommend applying weed and feed no more than two or three times per year, depending on the climate and the specific grass type. The ideal schedule typically involves an application in the early spring, once the grass has been mowed a couple of times and weeds are visible, and a second application in the early fall. Applying the product during the cool season aligns with the periods of active growth for most turfgrasses. Applying the product during the hottest summer months is discouraged because the high nitrogen content can weaken roots and increase vulnerability to heat stress and chemical damage.
Signs of Overapplication and Corrective Measures
Applying weed and feed too frequently or at too high a concentration can lead to significant damage, often described as fertilizer or chemical burn. Visual signs include rapid yellowing of the grass blades, followed by brown, scorched patches. The high concentration of nitrogen in the fertilizer component frequently causes this scorching, as it draws moisture out of the grass roots and leaves.
Beyond surface damage, overapplication can lead to root damage and an overall weakening of the turf’s health. Excessive chemicals also contribute to nutrient runoff, which is a concern for the surrounding environment. If signs of overapplication, such as brown patches or yellowing tips, appear, immediate corrective action is necessary to save the lawn. The primary step is deep, thorough watering to flush the excess chemicals out of the root zone and deeper into the soil. This process should continue for several days to dilute the concentration of the fertilizer and herbicide. Temporarily stopping all further fertilization is also necessary, allowing the stressed turfgrass time to recover before any new nutrients are introduced.