What Is Weed-and-Feed?

Developed as a lawn care convenience product, weed-and-feed combines an herbicide that kills particular weeds and a chemical fertilizer that provides nitrogen to the grass. The convenience lies in the single application. With one pass across the lawn, you can apply both an herbicide and a fertilizer.

How Weed-and-Feed Products Work

Each weed-and-feed product has a unique recipe for targeting weeds and fertilizing grass. The herbicides included are weed-specific. For example, many products include an herbicide to stop crabgrass before it emerges. Other products contain herbicides that zap dandelions and other broadleaf weeds.

The fertilizer component of each weed-and-feed is unique too. One product formulation might contain a fertilizer ratio that is well-suited for cool-season grasses while another product’s recipe might be geared toward warm-season grasses like Bermudagrass and zoysiagrass.

For a weed-and-feed product to be effective, it must target the weed species you are trying to control in your lawn, while satisfying the nutrient needs of your specific turf. Read the package label carefully to ensure the product aligns with your lawn situation.

Weed-and-Feed Timing

Researchers and turfgrass scientitsts have long questioned the effectiveness of weed-and-feed products. Here’s the issue: the timing is off in many cases. Applying the product at the right time to combat specific weeds doesn’t always correspond to the best time to apply the fertilizer product. But, since the weed-and-feed is an all-in-one product, one application is necessary and that might mean one of the two products is wasted.

This challenge is most visible with popular weed-and-feed products formulated to control crabgrass. The preemergent crabgrass herbicide must be applied in early spring. The lawn doesn’t need any fertilizer in early spring; in fact, early spring fertilizing causes a big flush of green top growth at the expense of the root system. The lawn then goes into summer with a weak root system that is less able to withstand heat and drought.

Additionally, it’s important to be aware of application frequency when using weed-and-feed products, as determined by environmental governing agencies. Application limits are generally no more than twice per year. Always read and follow package directions exactly.

Environmental Concerns

Weed-and-feed products are made up of synthetic herbicides and fertilizers. The environmental impacts extend beyond the target weed and your lawn.

First, weed-and-feed products that include preemergent herbicides will stop the growth of any seed they meet—from weed seeds to grass seeds. Preemergent herbicide remains active in the soil for six to eight weeks after application. If you are planning to overseed your lawn, do not treat the area with a weed-and-feed product containing a preemergent herbicide.

Next, weed-and-feed products that are applied early in the growing season often contribute excess nitrogen to local groundwater and streams. The fertilizer component of the weed-and-feed product is not absorbed by plant roots and can move through the soil profile into local groundwater or nearby streams.

Scientists have found that the roots of trees and shrubs are sensitive to repeated applications of weed-and-feed products over the plants’ root zones. The herbicide contained in the product are absorbed by the woody plant roots. Trees and shrubs may be able to withstand an annual application without much harm, but several applications can cause additional stress and eventually be lethal. Don’t use weed-and-feed products near trees and shrubs.

When Is Weed-and-Feed Helpful?

Use a weed-and-feed product when the weeds it controls and the type of grass it's formulated for match your lawn’s needs exactly. Take time to read the fine print on the packaging, paying special attention to application directions and caution statements. Don’t make assumptions; find answers to questions that arise.

For most lawns, it's best to avoid weed-and-feed products formulated to prevent crabgrass. To be effective at controlling crabgrass, the fertilizer is wasted and ends up polluting waterways.

Which Weed-and-Feed Products Are Best?

The best weed-and-feed product combats the weed population in your lawn and meets the fertilizer needs of your turf. Learn more about the fertilizer needs of your turf by taking a simple soil test to reveal your lawn’s nutrient needs. Pair the test report with the fertilizer formulation of the weed-and-feed product.