Weed & Feed products combine a lawn fertilizer with a weed killer and/or weed preventer in one product. One application does double duty, treating random weeds spread across an entire lawn while also feeding and greening grass. Weed & Feeds come in two basic formulations, granules and liquids. But before you make an application, here are some things you need to know about weed & feed products.
Weed & Feed Starts With Weeding…
The “weed” half of “weed & feed” contains some mix of herbicides to kill lawn weeds. Almost all products contain a post-emergent herbicide, but some also combine a pre-emergent herbicide designed to prevent new weeds from sprouting.
Post-Emergent herbicides kill existing lawn weeds like Dandelion, Clover and many other common weeds. The complete list of weeds can be found on your product’s label. These post-emergents are always selective herbicides, so they will not harm existing grass when applied as directed. New innovations, like BioAdvanced 5-in-1 Weed & Feed, also kill grassy weeds like Crabgrass, eliminating the need for multiple applications of additional herbicides to achieve control.
Pre-Emergent herbicides are meant to keep new weeds from germinating and growing. Timing is the key, apply too early and the preventer can become ineffective while weeds are still dormant. Apply too late and seeds may have already germinated. You’re probably most familiar with Crabgrass preventers that are applied in early spring.
…And Ends With Feeding
The “feed” half of “weed & feed” is all about fertilizer. Most fertilizers are a mix of nitrogen and other macro-nutrients, and sometimes micro-nutrients, in varying amounts. Nitrogen (N) is the most important element in lawn fertilizers and comes in two basic forms – fast-release and slow-release. Most lawn fertilizers include a mix of fast-release and slow-release forms to provide quick green-up and sustained growth.
Fast-Release Nitrogen (often referred to as water-soluble nitrogen or WSN) such as urea and ammonium sulfate, is readily available and absorbed quickly by the grass, resulting in fast green-up. Unfortunately, it can also can burn your lawn if applied improperly, and can leach through the lawns root zone or run off the lawn in heavy rain, causing pollution.
Slow-Release Nitrogen (often referred to as WIN or water-insoluble nitrogen), such as sulfur-coated urea, methylene urea and animal manures, are released more slowly to the grass and provide more sustained, even growth – up to 3 months for methylene urea.
Before You Begin, Know Your Lawn Type
Before applying any type of weed & feed or fertilizer product, you need to identify your type of grass. Some fertilizers can be applied to all lawn types, but most weed & feed products are specifically labeled for certain types of grasses. Apply the wrong product to the wrong type of grass and you can damage your lawn. Use caution and read the label. If you’re still unsure, use the toll-free number found on the label to contact the manufacturer.
When To Apply
Weed & Feed products are most effective when weeds are small and actively-growing, namely spring and fall.
In spring, wait to apply until you’ve mowed your lawn two times before applying to be sure it has emerged from dormancy.
In fall, be sure to check the with local Cooperative Extension System office for historical frost dates in your area. Many Weed & Feed labels will recommend application timing based on that date.
Most weed & feed products will have temperature restrictions as well, be sure to check the label. Do not apply to water-saturated soils, lawns under stress from drought, disease or prone to injury.
How To Apply
For liquid weed & feed products, be sure to use one of the sprayer types recommended on the label and follow label instructions for mixing and spraying.
For granule weed & feeds, use a rotary or drop-type spreader. Drop spreaders apply fertilizer very precisely in a narrow band directly below the spreader, while a rotary spreader broadcasts over a wider area. The application pattern is very important. Be sure to follow label instructions.
Both types of spreaders have adjustable application settings. How much fertilizer is applied varies according to the settings on the type and model of spreader you use. Read the spreader manufacturer’s instructions before fertilizing to help you calibrate your equipment to ensure proper application rates. You'll find the proper setting for your type of spreader on the specific fertilizer label. If not, there should be a toll-free phone number to call. Do not use the spreader until you are sure it is set properly. You can learn more about calibrating your spreader and spreader settings. Be sure to read always and follow label instructions.
Other Things You Should Know
Mowing – For best results, mow your lawn 1-2 days prior to application. Clippings from your next three mowings should be left on the lawn. Be sure not to use these clippings as mulch or compost around flowers, ornamentals, trees or in vegetable gardens.
Do Not Rake – Heavy raking will disturb the weed preventative barrier and reduce the effectiveness of this product.
Watering – Many weed & feed products instruct you to wait 24 hours before watering in. Be sure to consult your specific label.
Feeding New Lawns – Most new lawns don't need to be fertilized until 6-8 weeks after planting. However, that can vary depending on how the soil was prepared before planting and the type of fertilizer used. Consult your local Cooperative Extension System office or nursery for recommendations on fertilizing new lawns.