Will Overseeding Kill Weeds?

hand with grass seeds

hand with grass seedsOne of the most effective weed control techniques is overseeding.

Overseeding is mostly used to fill in bare spots throughout a lawn in an effort to produce a more dense, thick lawn.

Since this is a step to preventing weed growth, it should be no surprise that overseeding takes time and effort.

At different times of the year, given your circumstances, overseeding will allow you to gain an advantage against weeds.

Keeping up with regular lawn maintenance throughout the year is one way to fight weed growth in your lawn.


Many overseeding techniques and aftercare procedures can potentially promote weed germination. Therefore, it’s imperative to circumvent the weed competition.

For example, you need your grass seed to contact the soil. Otherwise, the grass won’t grow.

The problem with this is that if you start disturbing the ground, the chances are high that you’ll cause excessive weed seed germination by exposing those seeds to the soil.

The solution is to use a slicer or seeder, a tool that disturbs the earth as little as possible. A light-handed approach will also leave your existing lawn in better shape than if you used a power rake or dethatcher.

The best way to ensure seed-to-soil contact is to water lightly for several days after seeding, being careful not to water beyond working the seed into the soil.


core aeration
Aerated lawn

You’ll want to prepare the soil to be overseeded. The seeds have a better chance at survival if you aerate your lawn first.

Check out one of our other articles titled, “How Aeration or Seed Slicing Can Benefit Your Lawn,” for more information on aeration.

In North Texas, because we experience such high temperatures, you are able to aerate and then overseed, both in the fall and in the spring.

Lawn experts say to aerate when your grass is rapidly growing.

One thing to consider is the watering process. Once you overseed, you will initially need to water heavily.

After the grass seeds germinate, which usually takes 10-14 days, you can reduce the amount you’re watering.

It is important to leave the soil undisturbed at large to foster grass germination. Be aware though, that it will also encourage the germination of weeds.

Good germination is good germination, whether you want the specific vegetation benefitting from your efforts or not.

Soil samples will inform you if you need to supplement the seedbed with critical nutrients. Another hedge against weeds is mowing.

Mowing consistently will encourage turf to increase in density and control the weed population before they grow large enough to compete for resources against the turf.


A few times a year, you can take advantage of specific conditions to gain the edge your grass needs to defeat weeds. As I mentioned, early fall provides a time of reduced weed competition.

You can overseed and use the light watering and frequent mowing technique until the ground freezes for certain types of grass. The idea here is to regularly, yet lightly water to induce rapid germination while the weeds are dormant.

Within this process, take care not to overwater. Overwatering could provide the grounds for a disease to break out.

Suppose you choose to overseed before a hard freeze in late fall/early winter. In that case, winter’s freezing and thawing action will assist you in achieving seed-soil contact.

This is a risky move, mother nature coming in with a hard freeze after germination will likely damage your seedlings and hard and abundant rain in early spring could wash away all your hard work.

Let’s say come late spring or early summer, you find yourself in a losing battle. Even with proper irrigation, you may not win the battle against blazing temperatures and scorching heat.

You’ll need to employ the use of chemical agents here. Using an herbicide is the only way you’ll see any grass established.

Improper herbicide use will severely damage your seedlings and might even prevent germination altogether. It’s a risk; if you do this, you must do it deliberately and thoughtfully.

If you are worried about weed control and how to facilitate it for your lawn, contact JC’s Landscaping today.  We can assist you.


hand touching green lawnFinal Thoughts

Overseeding itself will not kill existing weeds.  Existing weeds will have to be removed through the use of an herbicide or by hand pulling.

The point of overseeding is to produce a more dense lawn, which will prevent new weeds from sprouting.

There’s a lot that goes into overseeding. It requires more than just throwing out a double portion of seeds and following the directions on the package.

Successful overseeding behooves deliberate action at the appropriate time. You’ve got to have a plan, and you’ve got to stick to it.

Now, the word turf was thrown around a bit here, intentionally. Overseeding is the process that the big-time turf growers use to provide lush football fields for the grueling gridiron season that sometimes extends well into late winter.

If it works on that more extensive scale, where the stakes are high, why wouldn’t you benefit from a similar regiment in your yard? 

Sometimes, knowing the right steps can save your whole operation. I’m not saying putting this knowledge to work for your lawn is going to secure victory, but at least if you keep these things in mind, you won’t have shot yourself in the foot:

  • Seedbed Prep
  • Planting Timing
  • Knowledge about diseases in seedlings
  • Proper Herbicide Usage
  • Following proper watering guideline
  • Using fertilizer correctly
  • Always having sharpened mower baldes

Stay flexible and pay attention. Overseeding isn’t a “written in stone” science. Every yard is a little different. 


M Valdivia

M Valdivia

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