Weed killer safe for new seed. How to Safely Kill Weeds in a Newly Seeded Lawn

We all know how frustrating it can be to see those pesky weeds pop up in your freshly seeded lawn. Did you realize that using weed killer on newly seeded lawns may actually harm the new seedlings? In this blog post, we aim to guide you through safe methods for managing these unwelcome intruders without harming your newly sprouted grass.

Keep reading; a weed-free and thriving lawn is just a few steps away!

Key Takeaways

  • Choose the right seed for your lawn to minimize weed growth and choose seeds with a built-in weed preventer.
  • Implement pre - emergent weed control methods like smothering the soil with mulch to block out sunlight and prevent weed growth.
  • Water enough for germination, then reduce water after germination, and fertilize and mow young seedlings regularly.
  • Address existing weeds by removing them individually before using weed killer and wait for the second mowing before applying any herbicides.

weed killer safe for new seed

Choosing the Right Seed for Your Lawn

When choosing the right seed for your lawn, consider the type of grass you want and select seeds that contain a weed preventer to help minimize weed growth.

Consider grass type

Choosing the right type of grass for your lawn plays a significant role in weed control. Various species of grass have different tolerances to weed invasions and resilience against herbicides.

For instance, cool-season types like Kentucky Bluegrass or Tall Fescue exhibit robust resistance against certain weeds but may be susceptible to others. On the other hand, warm-season varieties such as Bermuda or Zoysia Grass show a distinct toughness towards common Southern U.S. weeds but might struggle with some Northern invaders.

So having knowledge about your local climate and selecting the appropriate variety can help limit unnecessary weeding efforts down the line while maintaining an attractive lush green carpet across your yard with minimal use of harsh chemicals.

Select seeds with weed preventer

When choosing seeds for your newly seeded lawn, opt for ones that come with a weed preventer. These specially treated seeds are designed to inhibit the growth of weeds, giving your new grass a better chance to flourish without competition.

By selecting seeds with a built-in weed preventer, you can proactively tackle unwanted plants while promoting healthy growth in your lawn. This simple step can save you time and effort by reducing the need for additional weed control methods down the line.

So, make sure to look for seed varieties that include a weed preventer feature to start off on the right foot with your newly seeded lawn.

Implementing Pre-Emergent Weed Control

To prevent weeds from taking over your newly seeded lawn, there are several pre-emergent weed control methods you can implement. Smothering the soil with a layer of mulch will help suppress weed growth by blocking out sunlight and preventing weed seeds from germinating.

Additionally, nurturing your grass through proper watering and fertilizing will promote healthy growth, making it more resistant to weeds. Remember to choose a weed killer that is safe for new seedlings when dealing with existing weeds in your newly seeded lawn.


Smothering is a natural and effective method to control weeds in a newly seeded lawn. By covering the bare soil with a layer of organic material, such as straw or compost, you can block sunlight and prevent weed growth.

This suffocates the weeds and prevents them from taking root. Smothering also helps retain moisture in the soil, promoting healthy seed germination and growth. It's an eco-friendly approach that doesn't require any chemicals or harmful substances.

So, if you're looking for a natural weed killer for your newly seeded lawn, consider giving smothering a try.

Mulch Matters

Mulch matters when it comes to controlling weeds in a newly seeded lawn. Adding a layer of mulch around your seedlings can help suppress weed growth by blocking sunlight and preventing weed seeds from germinating.

It also helps conserve moisture in the soil, promoting healthy root development for your new grass. Organic mulches like straw or shredded leaves are great options that will eventually break down and enrich the soil with nutrients.

Just make sure to apply the mulch thinly to avoid smothering your delicate seedlings. By using mulch as a natural weed control method, you can give your new grass the best chance of thriving without having to resort to harsh chemicals.

Nurturing vs Nature

When it comes to weed control in a newly seeded lawn, there's often a debate between nurturing the new grass and letting nature take its course. While it may be tempting to rely on natural methods alone, like pulling up weeds by hand, sometimes additional measures are necessary.

Using a non-selective herbicide like glyphosate before seeding can help eliminate existing weeds and give your new grass the best chance to thrive. However, it's important to wait for at least three months after applying any weed killer before seeding to avoid harming the seeds or seedlings.

Balancing nurturing with nature is key when it comes to controlling weeds in a newly seeded lawn.

Watering and Aftercare

Water enough for germination. Reduce water after germination. Fertilize and mow young seedlings regularly.

Water enough for germination

To ensure successful germination of your newly seeded lawn, it is crucial to provide enough water. Watering enough helps the seeds absorb moisture and kickstart their growth process.

Consistent watering keeps the soil moist but not overly saturated, creating ideal conditions for germination. Remember that proper watering plays a significant role in the success of your new grass, so make sure to give it the right amount of water during this critical stage.

Reduce water after germination

After the seeds have germinated, it's important to reduce the amount of water you give your newly seeded lawn. While the seeds need sufficient moisture to sprout and establish roots, excessive watering can lead to shallow root growth and encourage weed growth.

Once the grass has begun to grow, gradually decrease the frequency of watering, allowing the soil to dry out between watering sessions. This will help promote deeper root development and make your grass more resilient against weeds.

Remember that newly germinated grass needs time to establish itself before using any weed control products or applying excessive amounts of water.

Fertilizing and mowing young seedlings

To help your newly seeded lawn thrive and combat weeds, it's important to provide the right nourishment and regular maintenance. Here are some tips for fertilizing and mowing young seedlings:

  1. Apply a slow-release fertilizer: Choose a fertilizer specifically formulated for new grass seedlings. Follow the package instructions and apply it evenly across the lawn. This will provide essential nutrients to support healthy growth without overwhelming the young plants.
  2. Mow regularly but not too low: Once your grass reaches a height of about 3 inches, it's time for its first trim. Set your mower blades to their highest setting to avoid cutting the grass too short, which can stress the seedlings. Aim to remove no more than one-third of the blade length at each mowing.
  3. Leave clippings on the lawn: Instead of bagging or raking up grass clippings, allow them to decompose naturally on the lawn. This "grasscycling" technique returns valuable nutrients back into the soil, providing additional nourishment for your growing seedlings.
  4. Adjust watering and fertilizing schedules: As your grass matures, adjust your watering and fertilizing routines accordingly. Gradually decrease water frequency while increasing watering depth to encourage deeper root growth. Follow a fertilization schedule that suits the specific needs of your grass type and local climate.
  5. Regularly monitor for weed growth: Keep an eye out for any emerging weeds in your newly seeded lawn. It's important to address them promptly before they have a chance to compete with your seedlings for resources.
  6. Consider natural weed control methods: If you prefer natural alternatives to synthetic herbicides, try manually removing weeds by hand or spot-treating them with organic weed killers that won't harm your new seedlings.

Addressing Existing Weeds

Once your newly seeded lawn has started to grow, you may notice some pesky weeds popping up. Don't worry - there are effective ways to address these unwanted plants without harming your new grass.

Learn how to remove them individually and when to use weed killer in our next section. Keep reading to find out more!

Remove weeds individually

To safely address weeds in a newly seeded lawn, it is important to remove them individually. Here are some steps you can follow:

  • Identify the weeds in your lawn.
  • Pull up the weeds from the base, ensuring that you remove the entire root system.
  • Use a gardening tool, such as a weeding fork or hand trowel, to gently loosen the soil around the base of the weed before pulling it out.
  • Dispose of the pulled weeds properly to prevent them from reseeding or spreading.

Wait for the second mowing before using weed killer

Before reaching for the weed killer, it's important to wait for the second mowing of your newly seeded lawn. Applying herbicides too soon can harm the new grass and seedlings. Taking this precaution allows the grass to establish itself before using any weed control products.

By waiting until after the second mowing, you give your new lawn a better chance of thriving while effectively addressing any weeds that may have emerged.

Use post emergent weed killer

To effectively address existing weeds in your newly seeded lawn, consider using a post-emergent weed killer. This type of weed killer is specifically designed to target and eliminate weeds that have already emerged from the ground.

It's important to wait for the second mowing before applying any weed killer to ensure that your new grass has had time to establish itself. By using a post-emergent herbicide, you can safely and efficiently eliminate unwanted weeds without harming your freshly seeded lawn.

Remember to follow the instructions on the product label and apply only as directed for best results.

Deal with crabgrass

Crabgrass can be a common and stubborn weed that invades newly seeded lawns. To tackle crabgrass, it's important to remove it manually by pulling it up from the base. This shallow-rooted weed can be easily removed by hand, making it an effective natural method of control.

By addressing crabgrass promptly, you can prevent it from competing with your new grass for nutrients and space to grow. Remember to continue monitoring your lawn regularly for any signs of crabgrass and address them as soon as possible to maintain a healthy and weed-free lawn.


In conclusion, killing weeds in a newly seeded lawn requires careful consideration and safe practices. Avoid using weed killer directly on new seedlings to prevent harm. Instead, manually remove weeds by pulling them up from the base.

Wait for the appropriate time before using herbicides to protect your new grass. With patience and proper care, you can maintain a healthy lawn free of weeds without harming your newly seeded grass.


1. Is there a weed killer that is safe to use on new seed?

Yes, there are weed killers available that are safe to use on newly seeded lawns. Look for herbicides labeled as "safe for new seed" or "pre-emergent" to prevent weeds from germinating without harming the grass seed.

2. Can I apply weed killer immediately after seeding my lawn?

No, it is not recommended to apply weed killer immediately after seeding your lawn. It's best to wait until the new grass has established itself and reached a height of 2-3 inches before applying any herbicides.

3. How long should I wait after using weed killer before reseeding my lawn?

It is advisable to wait at least 4-6 weeks after using weed killer before reseeding your lawn. This allows enough time for the herbicide to break down and become ineffective, minimizing any potential harm to new seeds

4. Are there alternative methods for safely killing weeds in a newly seeded lawn?

Yes, there are alternative methods for safely killing weeds in a newly seeded lawn. Hand pulling or spot treatment with vinegar or boiling water can be effective options that do not harm the newly seeded grass.