How Long After Spraying Roundup Can You Plant Grass Seed

While many people have turned to natural means of weed removal, sometimes, the only way to free your lawn of invasive plants is with herbicide.

One of the most popular non selective herbicides in the market is Roundup. Many homeowners use this product to help prepare their lawns for grass planting.

If you plan on applying Roundup to your lawn, make sure you follow the recommended guidelines. Otherwise, you risk severely affecting the growth of your plants, including your new grass.

What are Roundup Products?

Roundup is essentially glyphosate, which is a non-selective herbicide that kills most plants. Most people use it as a weed-killer. However, if you aren’t careful, it can destroy much more than just weeds.

This herbicide blocks a specific enzyme pathway that prevents the production of essential plant proteins. Once absorbed by plant tissues, it quickly spreads throughout the plant’s system and completely stops its growth.

On Sale
Roundup Ready-To-Use Weed & Grass Killer III -- with Sure Shot Wand, Use in & Around Vegetable Gardens, Tree Rings, Flower Beds, Patios & More, Kills...
762 Reviews
Roundup Ready-To-Use Weed & Grass Killer III -- with Sure Shot Wand, Use in & Around Vegetable Gardens, Tree Rings, Flower Beds, Patios & More, Kills...
  • Kills existing weeds and grass to the root. Guaranteed! Consumer Guarantee: If for any reason you...
  • Protective Shield fits over weeds to contain spray and help protect desirable plants
  • Use in and around vegetable gardens, flower beds, tree rings and mulched beds, as well as on cracks...
  • Visible results in 3 hours

When Should I Use Roundup on My Lawn?

The best time to apply Roundup before seeding depends on two factors: grass type and the weather.

Grass Type

If you plan on planting warm season grasses, you should apply Roundup in the fall, so your lawn is ready by the following spring. You should time it so that you plant no later than August or September.

For cool season grass, apply Roundup after summer, then wait for the weather to cool down in October before planting.

Weather

On windier days, Roundup can spread through other areas of your garden or lawn, potentially killing plants you want to keep.

Rainy weather can reduce the herbicide’s strength, so try to use your herbicide on a dry day. With that said, Roundup only needs 30 minutes to soak into your weeds, and it won’t get washed away by the rain after that.

How Soon Can You Plant After Using Glyphosate?

Roundup works best if you allow it to penetrate the weeds thoroughly. The herbicide needs time to reach and kill the root system to prevent re-sprouting.

Depending on the type of Roundup you use, you should wait at least a couple of days before planting grass after Roundup use. Depending on the product you use, you may have to wait for months before you can reseed.

Three Days

If you want to plant your grass as quickly as possible, you can use Roundup Weed and Grass Killer Concentrate Plus, Super Concentrate, or Ready-to-Use Plus variants.

According to the manufacturer, you should wait at least three days after planting to ensure healthy grass growth.

One Week

Some products, like Roundup Weed and Grass Killer Sure Shot Foam, take a full week to reach weed roots. If you have more time, these products work well and are often cheaper than their fast-acting versions.

Four Months

Some products, like Roundup Quickpro Dry Formula, contain diquat, another herbicide. This substance delays seed growth, and it can remain in your soil for many months.

How to Properly Plant Grass After a Roundup Application

Grass Growing
  1. Wait until the weeds in your lawn become completely brown. This process can take a few weeks or longer.
  2. Remove any debris, including rocks and branches, on your lawn that can damage your mower.
  3. Mow your lawn as close to the ground as possible. Work the mowed weeds into the soil by tilling 3-inches of the top layer.
  4. You can use a metal rake to level sloping areas in your lawn. Fill in any areas prone to water pooling.
  5. Apply grass fertilizer with a sower, and work it into the soil with a tiller.
  6. Plant your grass seed. Seed planters let you do the job much faster, but hand sowers work best for precision planting.
  7. Use the backside of a rake to work the grass seeds into your lawn gently. Don’t use too much force because it could damage the seeds or pack them too tightly into the soil.
  8. Gently water your lawn, enough to keep your seeds moist but not soaked.

Take Care of Your Weeds Before They Become a Nuisance

Using potent herbicides like Roundup should always be a last resort. Proactively dealing with weeds prevents them from turning into a more significant problem.

Manual Removal

Check your lawn every day and pull out roots to avoid new growth of weeds. You will find younger weeds with weaker root systems easier to remove.

Wet soil also loosens weeds so that you can remove the entire root system more efficiently.

Using Kneeling Tools

Kneeling tools make it easier to remove individual weeds. Depending on the weeds you have in your lawn, some tools may suit you more than others. Try these devices for a more comfortable and efficient weeding session:

  • Rake-type kneeling tools have thin prongs to scrape surface weeds with weaker root systems.
  • Hook neck tools and hand shovels can dig out larger weeds with deeper root systems.
  • Angled hand hoes can get into tight spots and take out weeds without damaging any of your surrounding plants.

Using Standing Tools

Standing tools are usually more expensive and less convenient to store, but they can easily remove multiple weeds. If you have an expansive lawn, these tools might work better for you:

  • Garden hoes can sever the roots of multiple weeds in one slice. Remember to get one with a padded handle for your comfort.
  • Grip-and-pull weeders work differently than your average garden hoe because they completely remove weeds from the soil instead of cutting them. Their sharp prongs can reach deep into the ground and pull out weed roots.
On Sale
Roundup Ready-To-Use Weed & Grass Killer III -- with Sure Shot Wand, Use in & Around Vegetable Gardens, Tree Rings, Flower Beds, Patios & More, Kills...
762 Reviews
Roundup Ready-To-Use Weed & Grass Killer III -- with Sure Shot Wand, Use in & Around Vegetable Gardens, Tree Rings, Flower Beds, Patios & More, Kills...
  • Kills existing weeds and grass to the root. Guaranteed! Consumer Guarantee: If for any reason you...
  • Protective Shield fits over weeds to contain spray and help protect desirable plants
  • Use in and around vegetable gardens, flower beds, tree rings and mulched beds, as well as on cracks...
  • Visible results in 3 hours

Author: Matt Hagens

Matt Hagens

Hi, I’m Matt the owner of Obsessed Lawn. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Learn more about me and find me on Facebook.