Cool Season Overseeding Steps

Prepare your lawn for overseeding

Preparation is key! Make sure you are mowing with a sharp blade for a clean cut, and lower your blade to 2-2.5 inches.

If you have more than half an inch of thatch on your lawn, dethatch so that the seed and fertilizer can penetrate the soil.

If your lawn is compacted, we recommend aerating before seeding to allow for deeper root growth. If you want to skip the heavy mechanical aerator, Lawnbright Aeroflow hooks up to your hose and sprays on to aerate.

Overseed patchy spots in late August

If you have cool season grass, late August is prime time to overseed the patchy spots in your lawn. Be sure to choose a high-quality seed and time the overseeding early enough in the season that grass has time to grow.

Use a broadcast spreader for even coverage.

Do not deal with weeds & seed at the same time

Wait at least two weeks after any type of herbicide to begin the overseeding process. You do not want to treat weeds and seed at the same time, as herbicides will also inhibit grass growth.

Fertilizer and water

Apply a starter fertilizer that is low in nitrogen and high in phosphorus to encourage root growth without pushing growth that dropping temps can't sustain.

Keep soil consistently moist until germination (1-2 weeks). Light and frequent watering works better than heavy soaking at this point.

Fall Lawn Care for Cool Season Grass (Zones 3–6)

  • Late August - Mid September = Prime Time

    ✅ Overseed with premium seed while soil is still warm

    ✅ Dethatch & aerate if needed

    ✅ Apply starter fertilizer (low-nitrogen, high-phosphorus)

    ✅ Spot treat weeds—but not if seeding

    ✅ Lower mower height slightly if overseeding

    Shop Natural Fall Overseeding Products 

Yard looks beautiful!

Oh my! We've only done 2 treatments and the difference in the yard already is remarkable! I've told lots of friends about your company and products already!

— Natasha A.

Real Results From Customers

  • Saved my lawn

    My lawn was looking terrible due to a hurricane/flooding. The local lawn service treated it for a few months and no changes. I cancelled them and started using Lawnbright. My lawn is looking better every week, almost back to pre flooding. The staff at Lawnbright is great, they respond quickly to my questions and their products are awesome!!!

    — Jim C., Verified Customer

  • Great quality seeds

    I’m really impressed with the RTF grass seed I got from Lawnbright. I’ve pre-germinated a few batches as I’ve been reseeding sections of my backyard & I’m also grew some RTF plugs to fill in spots if needed. Great product and awesome customer service. I will definitely order again very soon!

    — Thomas F.

  • So much better than other companies.

    We have been using lawncare services for years, went through multiple companies. They always seemed to cut corners or not get us the results we wanted. My husband researched and found Lawnbright. Our grass is so green even our landscapers mentioned how great the grass looked. 100% recommend

    — Kevin C.

Lawnbright Overseeding Collection

Overseeding Frequently Asked Questions

Q: Can I overseed and apply weed control at the same time?

A: No—most weed controls will prevent grass seed from germinating. Wait until your new grass has been mowed at least three times before applying weed killers.

Q:  Do I need to aerate before overseeding?

A: Aeration isn’t always required, but it improves results, especially in compacted soils.

Q: How long will it take to see results?

A: Germination can take 7–14 days, depending on seed type and weather.

Q: What’s the best temperature for overseeding?

A: Soil temperatures between 55–70°F are ideal.

Q: Is this safe for kids and pets?

A: Yes! All Lawnbright products are non-toxic and safe for families, pets, and the environment.

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