“Weed and Feed” is a popular dual-action lawn product that combines a broadleaf herbicide designed to kill weeds with a fertilizer to nourish the turf. The product aims to simplify lawn care by addressing two common issues—nutrients and weed control. For this combined treatment to work effectively, the sequence of lawn activities is important, and the answer is yes, you should mow before applying the product. This timing ensures the fertilizer reaches the soil and the herbicide makes adequate contact with the target weeds for maximum effectiveness.
Preparation: The Pre-Treatment Mowing Rule
Mowing the lawn a few days before applying a granular weed and feed product is essential for treatment. The ideal time to cut the grass is one to four days prior to application, with two to three days being recommended. This timing allows the weeds to recover slightly from the mechanical stress of mowing. They enter a phase of active growth where they are most vulnerable and ready to absorb the herbicide.
Cutting the turf to its normal recommended height ensures the fertilizer granules can easily filter down to the soil surface. When grass blades are excessively long, a significant portion of the granules can get caught in the dense canopy, delaying the release of nutrients to the root zone. Furthermore, the act of mowing helps to expose a greater surface area of the broadleaf weeds, which is necessary for the contact-based herbicide to work.
If the lawn is particularly overgrown, removing the clippings after mowing is advisable to prevent them from forming a barrier. Clippings can obstruct the path of the weed and feed granules, stopping them from settling onto the weed leaves and the soil. By clearing away the debris, you ensure the product has direct access to the target weeds and the soil where the fertilizer is needed.
Application: Maximizing Product Contact
The effectiveness of the weed-killing component in granular products requires firm contact with the weed foliage. Most post-emergent herbicides in weed and feed products require the granules to stick to the moist surface of the weed leaves, where the chemical is then absorbed. For this reason, the application should ideally occur when the leaves are damp, such as early in the morning when dew is present on the lawn.
If natural moisture is not available, a very light watering immediately before application can create the necessary surface moisture for the granules to adhere. Avoid applying the product during periods of extreme heat, generally when temperatures are above 90 degrees Fahrenheit. High temperatures can cause the herbicide to become volatile, potentially damaging the turfgrass while reducing the efficacy of the weed control.
A uniform application is accomplished using a rotary or drop spreader, often by applying the product at half the recommended rate in two overlapping passes. This technique minimizes the risk of uneven coverage that can lead to streaks of overly fertilized or poorly treated areas. Proper spreader calibration and technique ensure that the active ingredients are distributed consistently across the entire area, maximizing the opportunity for herbicide contact with every weed.
The Essential Post-Treatment Schedule
After the weed and feed product has been successfully applied, a specific schedule must be followed. The most immediate rule is to delay watering the lawn for 24 to 48 hours, as specified on the product label. This waiting period gives the herbicide granules sufficient time to dissolve and be absorbed by the weed foliage before being washed off.
Once the waiting period is over, a deep watering is required to activate the fertilizer component. Water helps move the nutrient-rich granules from the leaf surface down to the root zone of the turfgrass. This delayed, deep watering ensures that the weeds have absorbed the killing agent while the grass roots receive the necessary feeding for growth.
The next mowing of the lawn must also be postponed to prevent the removal of the partially absorbed weed killer. Cutting the grass too soon will clip off the treated portions of the weed leaves, effectively removing the systemic herbicide before it has had time to travel to the weed’s root system. A common guideline is to wait three to seven days after application before mowing again, ensuring the herbicide has fully translocated and begun its action against the weeds.