How Long After Using Weed B Gon Can You Plant Grass Seed?

Hunker may earn compensation through affiliate links in this story.
Image Credit: schulzie/iStock/GettyImages

When weeds are overwhelming the lawn, it may be time to consider an herbicide to clear out unwanted broadleaf and grassy weeds. Products like Ortho's Weed B Gon, available in ready-to-use sprays and concentrates, can eliminate the weeds without affecting common lawn grass species. Wait four weeks after using Weed B Gon to sow grass seed and fill in bare spots in the lawn.


Video of the Day


The minimum waiting period for sowing grass seed after using a Weed B Gon product is four weeks.

About Weed B Gon Products

Weed B Gon Weed Killer Ready-to-Use spray contains 2,4-Dichlorophenoxyacetic acid (2,4-D), mecoprop-p acid and dicamba acid. These herbicides target broadleaf weeds, such as clover and dandelions, but also affect a wide range of wildflowers as well as fruits and vegetables, fruit trees, vines and other ornamental plants. Weed B Gon Weed Killer should only be used on bahiagrass, bermudagrass, buffalograss, centipedegrass, fine and tall fescues, Kentucky bluegrass, ryegrass, St. Augustinegrass (except 'Floratam') and zoysiagrass lawns.

Another ready-to-use spray is Weed B Gon Chickweed, Clover & Oxalis Killer for Lawns, which contains triclopyr. Intended to eliminate persistent weeds like chickweed, clover, creeping Charlie, oxalis and wild violet, it can also be applied to buffalograss, fescues, Kentucky bluegrass, ryegrass and zoysiagrass. It can also adversely affect fruits, vegetables and ornamental plants.

If crabgrass has infested your lawn, Weed B Gon Plus Crabgrass Control may be able to eradicate it because it incorporates three herbicides: 2,4-D, quinclorac and dicamba. These herbicides eliminate broadleaf weeds like chickweed, clover and dandelion as well as grassy weeds like crabgrass and foxtail. This product is designed for use on bermudagrass, buffalograss, fine and tall fescues, Kentucky bluegrass, ryegrass and zoysiagrass lawns.

Safety Precautions and Herbicides

Put on chemical-resistant gloves, safety goggles, long sleeves, long pants, closed-toe shoes and a respirator mask before mixing or applying any chemical products, including Weed B Gon and other herbicides. After applying Weed B Gon, wash your hands while still gloved, then remove the gloves. Rewash your hands and any exposed skin with soap and water. Also, remove and launder your clothing as soon as possible.


Avoid applying to lawns on windy or hot days when temperatures are above 90 degrees Fahrenheit. If the lawn is bermudagrass, then refrain from application when the temperature is above 85 degrees F. If rain is in the forecast, wait to apply the herbicide until no rain is predicted for 24 hours after the application. Don't use Weed B Gon where it may run into storm drains or within 25 feet of wetlands, ponds or waterways; it is toxic to fish and invertebrates like crayfish and dragonflies.

Keep humans and pets away from the lawn until the herbicide is completely dry. Store Weed B Gon products in the original containers and keep them out of reach of children and pets.

Weed B Gon Application

Apply in spring or fall when the weeds are actively growing. Mow two days before treating the weeds, then wait at least two days to mow afterward and discard the grass clippings in the trash. Water the lawn 24 hours before applying Weed B Gon. If applying to a new lawn, wait until you've mowed at least three times to ensure the grass is firmly established.

Spot-treat the lawn by spraying the individual weeds, aiming at the center of the plant and lightly wetting the leaves. Wait at least 12 hours before watering the grass. Reapply Weed B Gon Weed Killer after 30 days or when weeds reappear, but no more than twice a year.

When treating persistent weeds like crabgrass or oxalis, use the appropriate Weed B Gon ready-to-use or concentrate product. Attach the sprayer to the garden hose, turn on the water, then slide the sprayer switch to "ON" and apply evenly across the lawn. Wait at least 24 hours before watering the lawn to ensure that the weeds absorb the herbicide. You can reapply Weed B Gon Chickweed, Clover and Oxalis Killer in 14 to 21 days and Weed B Gon Plus Crabgrass Control in 21 days, but no more than twice a year.


When to Sow Grass Seed

Wait four weeks after applying Weed B Gon products before sowing grass seed in the treated areas. Prepare the soil in any bare spots by loosening with a shovel and adding compost and other amendments as needed. Wet the area, then scatter the grass seeds. Press the seeds into the soil or compost with your foot or a lawn roller, cover with a light layer of sand, compost or straw mulch and water again.

Keep the area damp, watering once or twice daily if necessary, until the grass seeds germinate. When the grass is one-third taller than the recommended height, or four to six weeks after planting, it's time to mow. Leave the clippings on the lawn so they decompose and return their nutrients to the new grass.



Ruth de Jauregui is the author of 50 Fabulous Tomatoes for Your Garden. She writes numerous home and garden articles for a variety of online publications. She got her start as a book and cover designer in San Francisco for William (Bill) Yenne at American Graphic Systems. In addition to designing books, she wrote her first book, Ghost Towns. With several nonfiction books under her belt, de Jauregui recently published her first novel, Bitter.