Overseed a Lawn

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Overseed a lawn correctly and you can sit back and enjoy the newly planted grass for years to come.

Overseeding lawns is one of the easiest things you can do if you have thin turf and bare spots. How to plant grass doesn’t mean you have to rent a tiller or tear up the turf.

Having thick grass helps to stop weed seeds from germinating. Over seed and you’ll have thick turf preventing lawn weeds from growing. If there is no room for the weed to grow then controlling them is much easier.

Before beginning any kind of lawn renovation, try to have a soil test completed. Adjust the pH and add any nutrients that are lacking.


Best Time Of Year To Overseed

Over seeding a lawn can be done any time of year but there are optimum seasons. Seeding grass in cooler zones in the spring is what everyone wants to do. Unfortunately, you then have to deal with weeds for the upcoming season. You’ll also have to hope it germinates in time before the heat of summer.


When should I grow grass ?

  • Cool season over seeding is done in late summer until early fall.
  • Warm season lawns are to over seed in spring.

What You Will Need for Overseed

  • Organic Weed Killer
  • Aerator
  • Grass Seed
  • Lawn Starting Fertilizer
  • Spreader
  • Overseed Machine (rental)
  • Water


How To Plant Grass and Overseeding

Before you do anything, step back and observe your lawn. There may be a few things to do before you over seed.


  • Are there a large amount of weeds?
  • Do you feel that the soil is compacted?
  • Are there only small bare spots or holes that need repair?
  • Do you need to over seed entire lawn or just bare spots?


Do not use preemergent crabgrass fertilizer when you overseed.

Lawn Weeds

If weeds are prevalent in your grass, they should be sprayed a few weeks before you over seed the lawn. Spray the weeds with an organic herbicide, with enough time so they die and dissipate.

Organic herbicides are generally made with horticultural vinegar. Be careful overseed lawnwhen spraying, not to get it on any other plants or good grass. The organic herbicide will damage it. Where eye protection when using and only spray when it isn’t windy.

The lawn weeds should be actively growing for the herbicide to be effective. For optimal efficiency allow the weed to grow a bit before spraying. The more leaf surface you spray, the better your results.

You can find a great organic weed killer here.


Lawn Aerating

If there has been a lot of traffic on the lawn area in question, then your grass should be aerated. Whether it is a play area for children or a dog run, that traffic compacts soil and is probably why the needs over seeding.

over seedingYou can also assume the soil is compacted if you have been using chemical fertilizers and pesticides in the past. Those products and step program fertilizers hurt soil structure and contribute to soil compaction.

Don’t under-estimate the importance of aerating your lawn before you over seed. Aerating also provides the soil cores on top of the grass for the seed to adhere to. It’s nice to get some seed in the holes the aerator provides.

If you choose to use compost tea this would be a good time to spray the compost tea with mycorrhiza into the aerated holes. Here is a good place to find all your compost tea products.


How to Overseed a Lawn

So you’ve evaluated your lawn. You’ve sprayed any existing weeds and aerated the compacted soil. Now it’s time for the overseeding process. Make sure the grass is cut short before you start. You won’t be cutting it again for a few weeks. If you have an irrigation system, mark the sprinkler heads to prevent any damage to them.


Cut the Grass Short Before Overseeding


Renting a overseeder machine will cost around $50 for half a day. That should be sufficient time to complete most lawns. They will generally have push and self-propelled models. I prefer the self-propelled over seeder machine especially if you have any hilly areas. They cost a bit more to rent though.

To overseed a lawn is very similar to mowing. Pour your seed into the slice seeder hopper. Set the drop rate lever to what grass seed type you are using. The machine usually has the recommended levels on the machine. You can also inquire the setting of the overseeding machine with the rental agent.

Start the seeding machine and go a few feet and stop. Check to see how deep the tines are slicing into the soil. It should only be about 1/4 to 3/8 of an inch. Once your comfortable with the depth, proceed.

Try to stay in straight lines and overlap your wheel marks. Take your time the machine should be doing most of the work. Turning the machine can be a bit laborious. Be careful of walkways, driveways and especially sprinkler heads and the seed-slicing machine can damage them.

Once you complete overseeding the grass area, go over it again this time going perpendicular to first direction. Once again overlap the wheels.

When the job is completed, return the rented overseeder machine so you do not go over your rental time. Fill the machine with gasoline as they may charge you to refill it.
how to over seed
Lawn Seed Starting Fertilizer

Once you’ve completed the overseeding process, it’s time for the final step. Applying the starting fertilizer. I’ve seen so many people who put all the work into lawn seeding and then wonder why they weren’t successful. It’s usually because they avoided this step or were not aware of it.

Seed starting fertilizer is different from your typical “step” as it is developed specifically for lawn seeding.

Seed starting fertilizer typically has a higher phosphorus percentage than its counterparts of nitrogen and potassium. Phosphorus is important to seedling development. Phosphorus fertilizers are considered dangerous to the environment but in this one time, small amount it’s good to use.

Organic starting fertilizers are available if you choose. I always stress going the organic route if possible but in this case your success in over seeding is very important. If your grass is thick and plush after it’s been over seeded then the less problems you’ll have in the future. Which results in less pesticide use.

Our lawn care store has starting fertilizer.


Synthetic Seed Starting Fertilizer Is More Effective Than Organic

Fertilize your lawn and grass seed as you would normally and follow the instructions on the bag as how much to spread.  Don’t skimp on grass seed when you overseed a lawn.



The final step is to water the grass seed and existing lawn. Do not over water as this will cause erosion if there is any incline in your yard. Water lightly and keep moist until fully established.

Do not let the seed or seedlings dry out.


First Mowing

Mow the lawn after several weeks or until the grass has germinated and has grown to about 3 – 4 inches. Try to be careful not to disrupt the seedlings as much as possible.

Bag the clippings for the first few times you mow. Keep the lawn watered until the seedlings look mature.

Enjoy your new lawn!


How to Overseed a Lawn

  • If you want to forgo using the over seed machine – Aerate, spread seed, top dress with 1/2 inch layer of compost.
  • Another option is to aerate, seed, rake the plugs into grass seed, fertilize and water.
  • Using an over seeder is you best option.
  • If you only have some bare spots or holes go here.

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