“Weed and feed” products are a popular, dual-action solution that combines fertilizer to nourish the lawn and a selective herbicide to eliminate broadleaf weeds. This single application approach is designed to save time while promoting dense, healthy turf that naturally crowds out new weeds. Achieving the intended results depends significantly on the precise sequence and timing of your lawn care activities, especially mowing. Understanding the proper steps ensures that the fertilizer component is effectively absorbed by the grass roots and the herbicide fully contacts and kills the unwanted plants. Following the correct application window is paramount to maximize the product’s effectiveness.
The Critical Timing: Mowing Before Weed and Feed
The answer to the question of mowing before application is a definite yes, but the timing is highly specific. You should mow the lawn one to two days before spreading the granular weed and feed product. This short recovery window is deliberate, as it allows the actively growing weeds to develop fresh leaf surface area following the cut.
Mowing to your turf’s normal, recommended height ensures that the grass blades are not so tall that they shield the weeds from the herbicide particles. The granular formulation needs direct contact with the weed foliage to begin the absorption process. If the grass is too tall, the granules may simply collect on the grass canopy, preventing them from reaching the target weeds.
This pre-mow also removes excess organic matter that could interfere with the application. The ideal grass length ensures a clear path for the herbicide to adhere to the broadleaf weeds while helping the fertilizer component settle closer to the soil surface. Following this timing prevents the mechanical stress of mowing from coinciding with the chemical application, which could temporarily weaken the turf.
Understanding How Herbicides Work with Grass Length
The weed-killing component in these products is typically a systemic, post-emergent herbicide designed to control broadleaf weeds like dandelions and clover. A systemic herbicide must be absorbed through the weed’s foliage and then translocated throughout the entire plant, down to the root system, to be fully effective. This mechanism is why proper mowing timing is so important.
Mowing too soon before application would remove too much of the weed’s leaf surface, which is the primary site of herbicide absorption. Conversely, waiting too long after mowing allows the grass to grow tall enough to create a canopy that intercepts the granular particles, preventing them from reaching the low-growing weeds. The short delay of one to two days permits the weeds to begin growing again, ensuring a sufficient amount of foliage is available to capture the granules.
Once the granular product is spread, the active herbicide chemicals must stick to the leaves for a sufficient period to be absorbed. This absorption process allows the chemical to move through the phloem, the plant’s vascular tissue, to ultimately kill the entire weed, including the underground root structure. If the leaves are not present or the granules do not make contact, the herbicide cannot enter the plant’s system.
Essential Steps Immediately Following Application
After you have spread the weed and feed product, the next steps are primarily focused on activation and ensuring the herbicide has time to work. Most granular weed and feed products require the weed foliage to be damp so the herbicide particles will stick to the leaves. This dampness can be from a light watering immediately before application, or from morning dew, as specified by the product label.
The fertilizer portion of the product requires moisture to dissolve and release its nutrients into the soil for the grass roots to absorb. Therefore, the common instruction is to wait for a specific period, often 24 to 48 hours, to allow the systemic herbicide to be fully absorbed by the weeds before watering the lawn. Watering too soon can wash the herbicide granules off the weed leaves before the chemicals can penetrate the plant tissue.
You must also delay your next mowing to allow the herbicide to complete its work, with a waiting period of two to four days recommended. Mowing too quickly after application would physically remove the herbicide-coated weed leaves, clipping away the treatment before it has translocated to the roots. This waiting period is necessary to ensure the systemic herbicide has successfully moved throughout the weed for a complete, root-to-tip kill.