To properly reseed a lawn full of weeds, follow these steps:
- Seed your lawn in spring or fall.
- Kill weeds with a selective herbicide that won’t harm grass.
- Pull up the weeds once they are dead.
- Aerate your lawn to improve soil quality.
- Evenly spread a thin layer of compost on top of the soil.
- Spread your grass seed.
- Rake the compost to lightly cover the grass seed.
- Water your lawn and wait for the seeds to sprout.
This system will allow you to start your lawn with a clean slate. By killing off all the weeds before you reseed, you’ll give your grass seed a chance to sprout and establish itself. Once your new grass gets a foothold, weeds will have a hard time overtaking your lawn again.
Table of Contents
Will Grass Seed Drown Out Weeds?
Grass seed will not crowd out established weeds. In fact, the opposite is true. Because weeds are so fast-growing, they will steal water and nutrients your grass seed needs to sprout. So, if you spread grass seed on a weed-infested yard, the most likely outcome is that the weeds will kill the baby grass seedlings.
- Grass seed won’t outcompete weeds.
- Weeds will steal water and nutrients grass seed needs.
- A weedy lawn will kill grass seed.
- Destroy the weeds first, then seed your lawn.
Instead of trying to overseed a lawn to choke out weeds, it’s essential to get rid of the weeds first, provide the right soil nutrients, and then seed your lawn. Within weeks after following our process, you’ll have the beginnings of a beautiful weed-free lawn.
8 Steps to Reseed a Weed-Infested Lawn
When your entire lawn is overrun with weeds, spreading grass seed can feel like a waste of time. It is very hard for new grass seed to compete with aggressive weeds. To return your lawn to a pristine look, follow these steps:
Pick the Right Time
If you are growing warm-season grass, plan to reseed your weedy lawn in spring. This is the best time to seed your lawn if you are growing Bermuda grass, Centipede grass, Zoysia, or Buffalo grass. Wait until daytime highs rise to 80℉ (27℃), then start the process. Avoid seeding warm-season grass in peak summer heat—the seed can easily dry out and die.
- Plan to seed warm-season grass lawns in spring.
- Warm-season grasses grow in the American south and west coast.
- Seed your cool-season grass lawn in the fall.
- Cool-season grasses are found in the northeast and midwest.
Cool-season grass grows best when it is seeded in fall. So, if you are growing a lawn with Kentucky Bluegrass, Fescue, or Ryegrass, plan to reseed after the peak of summer. Wait until daytime temperatures drop down to 75℉ (24℃). Conditions at this time are ideal for sprouting cool season grass seed successfully.
Kill Off the Weeds
To successfully kill the weeds in your yard without killing your grass, use a selective herbicide. Selective herbicides target broadleaf weeds and pest grasses, but won’t harm most species of turfgrass. This allows you to kill off weeds without destroying all your grass, so you don’t have to start from scratch when you reseed.
- Use this selective herbicide to kill weeds without harming grass.
- Avoid using a non-selective herbicide, like Roundup. It will kill grass too.
- Spray the herbicide on the leaves of the weeds in your lawn.
Spray the selective herbicide on the weeds in your yard. Make sure to thoroughly mist the leaves of the weeds, since herbicides are absorbed through the leaves. Herbicides are designed to kill weeds down to the root, so they won’t come back. This makes spraying weeds much more effective than most other removal methods.
- Kills weeds without harming your lawn.
- You can expect results within only a few hours.
- Easy-to-use on a variety of grass types.
Remove the Dead Weeds
After spraying your lawn with the weed killer of your choice, wait 2 weeks for the weeds to die down to the root. Then, uproot the dead weeds to remove them from your lawn completely. Do not attempt to remove the weeds sooner than 14 days after spraying them with herbicide. Weed killers need 2 weeks to fully kill weeds. Pulling out the weeds too soon after they are sprayed could allow the roots to survive and sprout new foliage.
- Allow 14 days for the herbicide to kill the weeds to the root.
- Pull out the dead weeds to make room for new grass.
- Throw dead weeds in the trash so they don’t drop seeds on your lawn.
Dead weeds are usually easy to remove. You can wear gloves and pull them out by hand. Alternatively, you can use a rake, hoe, or other weed-pulling tools. Removing the dead plant material and roots makes it easier for new grass seeds to put down roots of their own. So, this is a crucial step in the process.
Aerate the Soil
Rent a core aerator from your local hardware store or tool rental supplier. This style of aerator is the best for lawns. Once you have your aerator, review the operating instructions. When you use the aerator, first push it across the lawn in a back-and-forth pattern, similar to mowing. Once you’ve completed this, use an up-and-down pattern to aerate the lawn from top to bottom. This results in well-aerated soil.
- Use a core aerator to loosen the soil in your lawn.
- Aerators can be rented from hardware and garden stores.
- First, aerate the lawn in an east-west pattern.
- Follow up by aerating in a north-south pattern.
- Make sure you use these tips for dealing with soil plugs after aerating.
Aerating your soil with a core aerator loosens the soil, which makes it easy for new grass seed to put down healthy roots. Plus, aerating allows more oxygen, water, and nutrients to enter the soil. A much higher percentage of your grass seeds will survive to adulthood if you aerate before seeding.
Topdress the Soil with Compost
Once your lawn is aerated, spread organic compost on top of the soil. You do not need a large amount of compost. The compost layer should be ½-inch (13 mm) thick across all areas of the lawn where you will spread grass seed. To achieve even coverage, make several small piles of compost on your lawn. Then, use a rake to spread the compost evenly across the soil surface.
- Spread this organic compost on your lawn.
- Use a rake to spread the compost until it is ½-inch (13 mm) deep.
- Do not bury desirable grass with compost.
- Allow compost to fill in holes left by aeration.
Do not bury any grass with compost during this step. Instead, gently spread the compost until it sits at soil level but does not smother any plants. It is fine if the holes left by aeration are filled with compost during this step. Compost breaks down quickly, so the soil won’t become compacted. Plus, when compost fills aeration holes it introduces nutrients deep into the soil, for your grass to use as it grows.
Spread Your Grass Seed
Load your grass seed into a handheld or walk-behind lawn spreader. Follow the instructions on the grass seed packaging to set the spread rate. Then, spread the grass seed across your yard by going in a side-to-side pattern, followed by an up-and-down pattern, just like you did when aerating. This leads to even coverage and more grass sprouts per square foot.
- Pour your grass seed into a lawn spreader, like this one.
- Follow the instructions on the grass seed bag to spread the right amount of seed.
- If you have existing grass, match your seed type to the grass in your lawn.
- If your lawn has no grass, choose a seed that thrives in your climate.
When choosing your grass seed, it is best to match the grass seed type to the variety of grass currently growing in your yard. Mixing and matching grass types can work in some cases, but can lead to patchy, mismatched yards in other situations. If your lawn has no grass, choose whatever seed you like, as long as it will grow well in your region.
Cover the Grass Seed
After you spread your grass seed, use a garden rake to lightly cover the seed with the compost you spread earlier. Grass seed performs extremely well when it is covered by ¼ inch (6 mm) of compost. This coverage prevents the grass seed from drying out and protects your seed from scavenging birds.
- Rake your compost to gently cover the grass seeds.
- Compost creates a moist environment that encourages more seeds to sprout.
- It is okay if some seeds are partially visible after this step.
- Find out why compost is better than topsoil when seeding your lawn.
It is almost impossible to fully cover each grass seed during this step. It’s okay for some of the seeds to be exposed or partially visible after raking the compost over the seeds. As long as the majority of the seeds are covered, raking compost over them will dramatically increase the seed’s germination rate.
Water Your New Seed
Immediately after you cover your grass seed, give it some water. Water for 10 minutes with a sprinkler. Then, continue watering your lawn twice daily until the grass seed sprouts. Keep these twice-daily watering sessions brief. 5 to 10 minutes of watering in the morning, followed by 5 to 10 minutes of watering in the late afternoon. This is essential because grass seed dies very quickly without water.
- Water your lawn for 10 minutes after you cover the seed with compost.
- Provide twice-daily water until the grass seed begins to sprout.
- Be careful with your new grass seed to help it survive.
- As the grass establishes itself, it will prevent weeds from invading.
For the first 2 to 4 weeks after seeding, your lawn must be kept moist. As the grass grows, gradually reduce watering to once daily, then once every other day. Remain patient as you water your new grass. As long as you provide adequate water and keep off your new grass long enough, your lawn will grow lush and weed-free.
How Do You Reseed a Lawn Full of Weeds?
Reseed a weedy lawn in spring or fall, not summer or winter. Start by killing off all the existing weeds and grass with a selective herbicide. Then, remove the dead weeds with a weed puller. Next, aerate your lawn to loosen the soil. This will encourage healthier grass seed growth. Spread a ½-inch layer (13 mm) of compost on the lawn. With the compost in place, spread your grass seed according to the coverage rates on the seed packaging. Use a garden rake to gently cover the grass seed with compost. All that’s left is to water your grass seed regularly, keep off the lawn, and wait for the new grass to grow in.