The product known as “Weed and Feed” (W&F) combines a broadleaf herbicide with a fertilizer into a single application, offering a time-saving approach to lawn care. This dual-action nature often confuses homeowners regarding the correct timing of application relative to mowing. The optimal schedule is dictated by the component requiring the strictest adherence to timing: the weed-killing agent. The schedule must allow the herbicide to work effectively without compromising the fertilizer’s benefit or the lawn’s health.
Mowing Rules for Effective Weed Control
The mowing schedule is primarily determined by the herbicide component of W&F, which is often a granular formulation for post-emergent broadleaf weed control. These systemic herbicides must be absorbed by the weed foliage and translocated down to the root system for a complete kill. Success depends on maximizing the available leaf surface area and ensuring the product remains undisturbed on the leaves.
Mowing immediately before application is discouraged because it removes the leaves, the primary point of entry for the herbicide. It is recommended to mow two to four days before applying W&F. This allows weeds to recover and present enough leaf surface area to absorb the active ingredients. This waiting period ensures the weeds are actively growing and more susceptible to the systemic action of the chemical.
After application, mowing must be delayed so the herbicide granules can stick to the weed foliage and penetrate the plant tissue. Mowing too soon physically removes the granules, dramatically reducing effectiveness. The recommended waiting period before the first post-treatment mow is typically two to four days, though up to seven days may be needed for difficult weeds. This window allows the herbicide to translocate completely to the root zone, ensuring the entire weed structure is impacted.
Mowing Rules for Fertilizer Absorption
The fertilizer portion of W&F is less sensitive to mowing timing than the weed killer, but considerations apply for maximum nutrient uptake. Since fertilizer is a soil-based treatment designed to feed grass roots, the main concern is getting nutrients into the soil quickly and preventing removal by the mower. Granular fertilizers are formulated to break down slowly, releasing nutrients into the soil over time.
Mowing before applying W&F is preferred because it prevents fertilizer granules from being picked up and discarded with grass clippings, which wastes product. If mowing occurs immediately after a granular application, the granules may be scattered by the mower’s action. Therefore, it is safer to mow a few days before the application to allow the fertilizer to reach the soil surface unimpeded.
If the W&F product is a liquid spray, the fertilizer is absorbed through the leaves, similar to the herbicide component. Waiting at least 24 to 48 hours after a liquid application before mowing allows the nutrients to be fully absorbed. The strict, leaf-contact requirements of the herbicide remain the primary driver of the entire W&F mowing schedule.
Essential Preparation and Follow-Up Steps
Successful application of granular W&F depends heavily on proper lawn preparation. Granular broadleaf herbicides require damp weed foliage, as moisture allows the dry granules to stick to the leaves and facilitates the transfer of the active ingredient. Applying the product in the early morning when dew is present, or lightly watering beforehand, is necessary for adhesion.
The temperature during application is relevant, with the ideal range for most W&F products falling between 60 and 90 degrees Fahrenheit. Applying during extreme heat can stress the grass and increase the risk of “burning” the turf due to the fertilizer’s salt content. The product should be applied using a calibrated spreader to ensure even distribution.
After the initial application, a waiting period of two to four days without watering is necessary for the systemic herbicide to work into the weed’s root system. Watering too soon washes the granules off the leaves before absorption is complete, rendering the weed killer ineffective. Once this waiting period is over, the lawn should be thoroughly watered to activate the fertilizer component, allowing nutrients to dissolve and move into the soil.