A combined “weed and feed” product offers the convenience of delivering both fertilizer and herbicide to your lawn in a single application. This dual-purpose treatment is designed to nourish the desirable turfgrass while simultaneously eliminating unwanted broadleaf weeds like dandelions and clover. Successfully using this product, however, depends entirely on precise timing relative to your mowing schedule. The straightforward answer to whether you should mow before application is yes, but the specific number of days you wait determines the product’s effectiveness.
Understanding the Herbicide Mechanism
Mowing timing is important because of how the herbicide component works. Most weed and feed products use selective, post-emergent herbicides formulated to target broadleaf weeds without harming the narrow-leaf turfgrass. These herbicides work by mimicking plant growth hormones, which causes the weeds to grow abnormally and eventually die.
For this process to begin, the herbicide must be absorbed through the weed’s foliage, meaning it needs maximum leaf surface area to make contact. The herbicide is a contact killer that must stick to the leaf and be translocated, or moved, down into the weed’s root system to kill the entire plant. If the leaves are too short, the amount of herbicide absorbed is significantly reduced, which can lead to ineffective weed control.
The fertilizer component, or the “feed,” works differently, primarily by dissolving into the soil and being taken up by the grass roots. By giving the turfgrass a boost of nutrients, the fertilizer encourages dense growth, which helps the lawn naturally outcompete new weeds.
Mowing Rules Before Applying Weed and Feed
To maximize the weed-killing power of the product, you should plan to mow your lawn a few days before application. The ideal window is typically one to three days prior to applying the weed and feed. This timing allows the weeds to recover from the stress of being cut and exposes a maximum amount of leaf tissue for the herbicide to land on and be absorbed.
Mowing too close to the application time, such as on the same day, removes the necessary leaf surface area that the weeds use to absorb the chemical. Research indicates that delaying mowing by 48 hours before treatment can increase the potency of weed controls by 30 to 40 percent.
Do not cut the grass blades too short, as this can severely stress the turf. Maintaining your normal recommended cutting height ensures that the herbicide granules or spray can easily reach the broad leaves of the weeds beneath the grass canopy. For granular products, the mower deck should be set high enough to allow the particles to settle onto the weed foliage, not just the soil.
Post-Treatment Care and Mowing Wait Times
After applying the weed and feed, a waiting period is necessary before you mow again to allow the herbicide to complete its work. You should wait a minimum of two to four days before the next cut. Mowing too soon will clip off the herbicide-coated weed leaves, which prevents the chemical from being fully translocated down to the root system, allowing the weed to survive.
Granular weed and feed products often require the weed foliage to be slightly damp before application so the granules stick to the leaves. However, heavy watering should be delayed for 24 to 48 hours after application to allow the contact herbicide time to penetrate the weed tissue before the water washes it away.
Once the waiting period is over, a thorough watering helps the fertilizer component dissolve and move into the soil to begin nourishing the grass roots. Always consult the specific product label, as formulations can vary and have precise requirements for watering and mowing intervals.