How Long After Spraying Roundup Can I Plant Grass

How Long After Spraying Roundup Can I Plant Grass?

Roundup suggests waiting one full week or 7 days, before planting or reseeding grass after spraying their product. 

This is so that the Roundup has sufficient time to move to the roots of any weeds that have been sprayed, and make sure the spray dissipates completely before planting new grass.

If you don’t wait long enough, the Roundup could end up killing the grass you’re trying to plant as well, because the spray is so effective at killing almost all plants.

How Roundup Works

Takes Time To Work

Roundup will typically enter a weed as soon as anywhere from 1-6 hours, at which point the surface will have dried and the plant is now safe to be near, but the actual time needed for the weedkiller to make its way to the roots of weeds can take much longer, often several days.

Roundup is very effective at killing plants, regardless of the type of plant, so it is very important to make sure you’re only spraying where needed.

The active ingredient in most Roundup products is Glyphosate, a systemic weedkiller that works by being absorbed through the leaf on the surface into the growing points of the plant, and eventually the roots, causing the plant to die.

Larger weeds will require more Roundup, and more time in order for the weedkiller to be completely absorbed into the roots. This could require spraying the same weed multiple times depending on the size and strength of a given plant.

Leftover Residue

It’s important to vacate areas that you’ve sprayed with Roundup until the spray has dried at least on the surface, after which the weedkiller will have been absorbed into the plant itself, at which point it is okay to return to an area treated by Roundup.

Failure to wait until the weedkiller has dried before returning to an area you have sprayed can lead to you unintentionally spreading the Roundup to other plants, for example, the grass in your lawn, and killing those plants in addition to the weeds. 

Roundup is extremely effective on grass because it works through it so quickly, so take extra care to avoid spraying grass and making sure you wait until the surface you have sprayed has dried completely before going near it again. This process normally only takes a few hours.

Using Roundup Safely

Using Roundup properly is very important to your safety, in addition to the well-being of your lawn.

Roundup, when used in accordance with the labels/instructions listed on the product, works effectively and safely. Make sure you adhere to all labels to ensure you get the desired result of the product while keeping yourself and others from spreading the Roundup to unwanted areas of the yard.

When applying Roundup, it is recommended that you wear closed shoes, gloves, and protective glasses to prevent the spray from going somewhere unintended, but protective clothing is not required when using the product.

Stronger and bigger weeds may require more than one treatment of Roundup on a given area, and will typically require slightly more time to be killed.

Different Types of Roundup

There are several different types of Roundup, each designed to deal specifically with different types of plants and/or areas that need to be treated.

Roundup Pump ‘N Go Sprayer is the most common of the Roundup product.  This product is used along with a pump and a nozzle almost like a hose, used to spray Roundup onto general areas where many weeds are present.

 Depending on the specific type of weed that you are trying to treat, you may need to alter the amount of Roundup concentrate that you will need to use. Be sure to adhere to the measuring guide displayed on the product to ensure you are using the right amount.

Roundup Gel is used to treat smaller areas that may contain certain plants that you do not wish to be treated with Roundup, so by using Roundup Gel, you are able to specifically treat the plants that you want going instead of spraying an entire area. 

Roundup Gel is very effective in gardens where there are weeds but also many plants that you would not want to be affected by the Roundup.

How Frequently Can Roundup Be Used?

Roundup can be used as needed on bigger and tougher weeds. If unwanted weeds remain a week after you have sprayed them, spray again as needed and make sure you are using the proper concentration of Roundup if using the spray version of the product.

Planting Grass

After you have treated an area with Roundup and waited the required time for it to dry and entirely kill the weed (normally about a week), you are able to plant grass in the treated area. 

You’ll want to first make sure you rake any dead plants out of the area you wish to seed, preventing the weeds from simply growing again in the same exact place.

Then you can proceed to plant the grass seed, ensuring it is properly maintained until the point where it is healthy enough and able to sustain itself. 

Failing to maintain your new planted grass seed until it is healthy enough to take care of itself can lead to the grass dying, meaning you will have to plant it all over again.


Waiting one full week after you’ve sprayed an area with Roundup allows enough time for the weedkiller to completely kill the weeds that have absorbed the Roundup, and for the Roundup to dissipate and go away so that the Roundup doesn’t end up killing the grass you are trying to plant.

Roundup is very effective at killing nearly all plants, so be sure to only treat areas/plants that you wish to remove.

Stay clear from any areas where you have used Roundup until the area is dry so that you do not spread Roundup to other parts of your yard, where it could kill plants you don’t intend to kill. This process normally takes a few hours, and then you can return to the area as normal.