Weed and Feed products have been designed, ostensibly, to cut down on the labor and time required to separately apply fertilizer and herbicides to lawn grass. The products applied together will prevent or kill unwanted weeds in the lawn and fertilize the desired grass species. The herbicides can be pre- or post-emergent and are usually selective herbicides so a product must be chosen that will protect the species of lawn you want to preserve and kill just the weed that has invaded the lawn. This can make choosing the right product tricky as you need to know the species of both, with the wrong choice being problematic for your lawn or even nearby plants. The zippy name somewhat belies the thoughtful and careful way these products must chosen and applied.
Opt for a weed and feed product, over standalone applications, to treat a significant and persistent weed problem you have noticed but not in lieu of your regular fertilizer. When using pre-emergent herbicides you need to base the need on the type and amount of weeds observed the previous season.
Identify the species of your lawn grass and the species of weed that you are looking to control. Determine whether the weed species is more susceptible to being controlled by a pre-emergent or post-emergent herbicide. Identify the time in its life cycle that your specific weed species is most vulnerable. This information determines what weed and feed product to apply and also when to apply it.
Determine the recommended dose of weed and feed product for your grass and acreage by consulting the product label directions.
Apply the product over the surface of the lawn at the label-recommended rate using a drop spreader or by hand casting. Set the drop spreader to the recommended aperture setting, and if hand casting, don garden gloves. Spread the product evenly over the lawn area and water it well, unless advised otherwise by the product label directions.
Refrain from using weed and feed products on lawns that may be above live tree roots as this can lead to tissue death and tree poisoning. Consult the product label and determine whether it can be used anywhere near the drip line of your tree before applying.