Will Grass Grow Back After Roundup? (When to Replant)

Roundup is a popular glyphosate herbicide used in most parts of the U.S. The product indiscriminately kills weeds and other plants upon contact. This is why gardeners, farmers, and foresters rely on it to control invasive plants. So, will the grass grow back after the roundup?

The answer is no: Grass will not grow back after being sprayed with roundup. This chemical herbicide completely kills grass and weeds to the root, and there will be no regrowth. Therefore, use it only on unwanted plants.

Will Grass Grow Back after Roundup?

Roundup comes in different formulations for various targets. Roundup with glyphosate, an active ingredient, is a non-selective herbicide that kills any green plant it comes into contact with.

Glyphosate Roundup is great for use in areas where you don’t need any plants to grow, like on driveways, pea gravel patios, and pavers. You can also use it to get rid of a lawn full of weeds and start afresh.

Round up for lawns is formulated for controlling weeds in turf grasses. It does not contain glyphosate. When used as directed, this selective herbicide will not kill your lawn grass but will target specific weeds such as dandelion, nutsedge, and crabgrass, among others.

How Does Roundup Work?

When choosing an herbicide, it is important to understand how the product works and its active ingredients. This is the only way to recognize its effects on your desired plants and soil.

The active herbicidal ingredient in Roundup is glyphosate, which targets an enzyme essential to plant growth. After applying Roundup, glyphosate works its way through the plant, from leaves down to the root. Then after a few hours, the plant will start wilting and eventually die completely.

Since Roundup completely destroys a plant from the leaves to the roots, there are no chances of regrowth. Glyphosate kills almost all plants it incomes into contact with, so even the non-targeted plants will not be spared if the herbicide accidentally drips onto them.

How long does roundup take to kill weeds?

Roundup takes as little as 12 hours to start killing the weeds and up to 7 days to accomplish the mission completely.

Although you may replant the area in as little as 3 days for some formulations, you should allow your herbicide enough time to avoid the risk of weeds re-sprouting from any viable roots.

When applying Roundup, it is possible that a few droplets will end up in the soil. Glyphosate may take several days in the soil before it completely disintegrates. However, it may not interfere with any new plants as long as you wait before replanting as directed on the product label.

The exact time it takes for glyphosate to break down in the soil remains a point of discussion. This is mainly because the rate of disintegration gets affected by various factors such as the amount of herbicide sprayed, the intensity of rainfall in an area, soil temperature, and humidity.

When to Replant after Using Roundup

According to the Roundup weed killer manufacturer, replanting the treated area after three days with lawn grasses, fruits, or vegetables is safe.  Shrubs and trees can be planted the next day after using Roundup.

I usually wait for seven days to regrow after using Roundup. This gives the herbicide enough time to kill all the weeds completely. This also helps me clear any doubt about the herbicide affecting my seed or new plants.

Is Roundup safe?

The use of Roundup in agriculture has created a critical debate among international health organizations. For example, in 2015, the World Health Organization’s International Agency for Research on Cancer (IARC) declared that glyphosate was a probable carcinogen to humans.

However, The Environmental Protection Agency (EPA) and the European Food Safety Authority (EFSA) table various risk assessments which do not agree with the findings and therefore declare glyphosate safe to use in pesticides.

This ignited mixed reactions in various cities, states, and countries around the world, some of which have banned the use of Roundup in controlling weeds, especially in agricultural fields.

Like any other herbicide, Roundup is harmful when ingested by humans, pets, and other animals. Use it with caution and away from children and pets. Always read and follow the provided safety guidelines before and after use.

How to use Roundup safely

Using Roundup correctly enhances safety and provides accurate results in controlling weeds. Here is how to use Roundup herbicide:

  1. First, ensure that you use Roundup on plants you do not want. As you know, glyphosate indiscriminately kills any plant it comes into contact with.
  2. Next, choose the right formulation for your garden or farming needs. Roundup comes in various formulas that have different ingredients for various applications.
  3. Carefully read and follow user instructions on the product label. This includes safety guidelines and timelines before replanting.
  4. Wait to spray your roundup when the weather is calm and dry. Avoid rainy or windy days as you don’t want the herbicide to be blown to other desired plants or washed away into the nearby water sources.
  5. Apply Roundup directly on the leaves of the weeds or plants you want to kill. Do not spray it on the soil.
  6. Safely store any remaining product in an area that is not too hot or too cold and away from the children.

Final Thoughts

Roundup is undoubtedly effective in killing stubborn weeds in yards, gardens, and agricultural fields. When used correctly, no grass or weed will come back after Roundup.

Be sure of where you want to use this herbicide to avoid killing your lawn or flower garden. Also, remember to read and follow use instructions provided by the manufacturer.

Also Read: Best Dandelion Killer that won’t Kill Grass


  1. Difference between Roundup and Roundup For Lawns – Michigan State University Extension
  2. How do roundup work – Roundup.com

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