The term “weed and feed” describes a convenient combination product that merges a lawn fertilizer with a selective herbicide. This single product aims to nourish the grass while simultaneously eliminating or preventing weeds, avoiding two separate applications. Because of the variety of formulations available, there is no single “best” option for every lawn. Choosing the most effective product requires understanding your specific lawn type, the weeds you are targeting, and the precise timing dictated by your local climate.
Deconstructing Weed and Feed Products
Weed and feed products contain two primary components: the “Feed” and the “Weed” portion. The “Feed” is a granular fertilizer formulated to supply the macronutrients necessary for turf growth. This content is displayed as the N-P-K ratio, representing the percentage by weight of Nitrogen (N), Phosphorus (P), and Potassium (K). Nitrogen is the most crucial for stimulating lush, green, above-ground growth.
Phosphorus supports strong root development, while Potassium helps regulate water uptake and increases the grass plant’s resilience to stress and disease. Manufacturers often use a combination of fast-release nitrogen for immediate green-up and slow-release nitrogen for sustained feeding. The “Weed” component is a selective herbicide designed to eliminate broadleaf weeds without harming the grass.
The herbicide component typically falls into one of two categories: pre-emergent or post-emergent. A pre-emergent herbicide functions as a preventive measure, creating a chemical barrier that stops weed seeds, like crabgrass, from successfully germinating. Conversely, a post-emergent herbicide is a reactive treatment that targets and kills existing, visible weeds, such as dandelions and clover, by being absorbed through their foliage. Most common homeowner products use a post-emergent herbicide blend, often including 2,4-D and Dicamba, to control a wider range of broadleaf invaders.
Selecting the Right Formula Based on Lawn Needs
Selecting the right product depends on the specific needs of your turf and the weeds present. The most critical factor for pre-emergent formulas is timing, which must be based on soil temperature, not the calendar. To prevent summer annual weeds like crabgrass, the product must be applied when the soil temperature at a two to four-inch depth consistently reaches 50 to 55 degrees Fahrenheit for several days. Applying too early risks the herbicide barrier degrading before germination, while applying too late allows germination to begin.
Matching the product to your grass species is equally important, as herbicides safe for one type of grass can damage another. Cool-season grasses, like Kentucky Bluegrass, Fescue, and Perennial Ryegrass, are generally more tolerant of a wider range of herbicides and are actively growing during the spring and fall. Warm-season grasses, such as Bermuda, Zoysia, and St. Augustine, grow most vigorously in the hot summer months but are highly susceptible to herbicide injury while transitioning out of winter dormancy. Products formulated for southern lawns often contain different herbicide compounds to ensure compatibility with these sensitive varieties.
Successful weed control requires correctly identifying the weeds you are battling. Post-emergent weed and feed formulas are highly effective against broadleaf weeds, which are characterized by net-like veins and include pests like plantain, henbit, and clover. However, these products are often less effective against grassy weeds that have already emerged, such as mature crabgrass or nutsedge. If grassy weeds are the primary problem, a separate, specialized control product may be necessary to supplement the weed and feed application.
Critical Application Procedures for Effectiveness
Once the correct product is selected, proper application is necessary for effectiveness. Granular weed and feed must be applied using a calibrated spreader, such as a rotary or drop spreader, to ensure uniform coverage across the entire lawn. The spreader setting must match the specific product and model being used, as incorrect calibration can lead to over-application that burns the grass or under-application that results in streaking and ineffective weed control. To maintain uniformity, passes should be slightly overlapped, and the spreader should be closed when turning to prevent excessive dumping.
The grass must be damp during application for post-emergent granular products. The grass blades must be damp, either from dew or a light sprinkling, so the herbicide granules stick to the weed foliage. This adhesion allows the weed to absorb the herbicide and ensures the product works as intended. Following application, you must delay watering or rainfall for 24 to 48 hours to give the herbicide sufficient time to translocate within the weed before the fertilizer component is watered into the soil.
Safety and environmental stewardship are important considerations during application. Always wear appropriate personal protective equipment (PPE) as directed on the label, and keep children and pets off the treated area for the recommended time, usually until the granules are no longer visible or the area is completely dry. Granules that land on hard surfaces like sidewalks or driveways should be swept back onto the lawn to prevent runoff into storm drains. Grass clippings from a treated area should not be used as compost or mulch in vegetable gardens for several weeks, as the herbicide residue may harm sensitive plants.