How long after overseeding can I mow?

Mowing a lawn

Typically, you’d wait two to four weeks between overseeding your lawn and the first mowing to ensure healthy growth and strong roots. But not all grass grows at the same rate. To know precisely how long after overseeding you can mow the lawn, you must consider a few key factors and know some practical mowing tricks.

Read this article to learn more about how mowing too soon or the wrong way can damage new grass and how long to wait after overseeding to ensure you grow a thick, beautiful lawn.

What is overseeding?

Professional Caucasian Gardener Spreading Seeds on the Lawn Using Garden Spreader Tool.
Photo Credit: Adobe Stock

Overseeding is spreading seed over an existing lawn to improve its thickness, repair brown patches and bare spots, or introduce new grass varieties. Successful overseeding requires careful preparation, including:

Short mowing before overseeding is essential. It buys the new seedlings time by ensuring the established grass doesn’t grow too tall too fast, shading and smothering the young plants. 

“To reduce the competition from the established turfgrass, mow the lawn at a height of 1-1/2 to 2 inches, says Dr. Richard Jauron, ​Horticulture Specialist at the Iowa State University Extension.

Spread the grass seeds with a drop or a broadcast spreader to ensure even coverage. Lightly raking the seeds helps them settle better into the soil. 

How long after overseeding can you mow the lawn?

After carefully spreading the seeds over bare spots and thin patches, you’re excited to see the results and mow the lawn for the first time. But when exactly is the best time to start mowing after overseeding? 

Wait at least two to four weeks

Give the new grass two to four weeks before driving a lawn mower over the lawn. This allows the newly planted turf to spread its roots deeper and anchor better into the soil, with a lower risk of pulling it out while mowing your turf. 

Here’s how Oregon State University explains the root growth timeline: “The roots of grass plants are sent deeply into the soil before much emerges from the soil surface. This gives a foundation for growth. For example, 2-3 inches of root are developed before a shoot emerges. The root may reach 6 inches in depth within two weeks.” 

What if you’re in a hurry? Some homeowners say you can mow the grass even after four days. However, the general opinion is to wait at least 10 days after spreading the new grass seeds to avoid severe damage.

Use new grass height as a reference

Grass growth happens at different speeds depending on turf type, weather, and lawn conditions. Use the height of your newly grown grass as a more precise reference for deciding the time of the first mowing. Vijai Pandian, a regional Horticulture Extension Educator for Milwaukee, Kenosha, and Racine Counties, advises mowing only after seedlings reach 3 inches tall.

What can change the waiting time?

Grass seed species: Slow-growing species like Kentucky bluegrass and buffalograss germinate in 10 to 30 days, requiring more time to develop until the first trim. On the other hand, ryegrass can pop up seedlings out of the soil in five days and be ready for mowing in about two weeks.

Weather: Heat and drought can dry out the soil, making it more difficult for new plants to grow. On the other hand, mild, cool weather with plenty of rain can speed up germination and seedling growth.

Seeding technique: Grass seeds broadcast over the soil take longer to germinate than slice seeded grass – seeds are pushed into the ground with a special machine.

What happens if you mow too soon after overseeding?

Man mowing lawn with a lawnmower
Photo Credit: Adobe Stock

Cutting the grass too early after overseeding usually means cutting it too short, damaging both the foliage and the roots.

Dr. James B. Beard of the International Sports Turf Institute explains, “The higher the cutting height, the greater the leaf area for photosynthetic activity to produce carbohydrates in support of increased root growth.” 

Let your newly planted grass grow a bit of leaves and some good roots before starting to mow.

Mechanical damage is also a risk. Foot traffic and driving a heavy lawn mower across a newly seeded lawn can wreak the fragile new grass. You risk:

  • Compacting the soil and blocking sprouts from popping up.
  • Uprooting seedlings.
  • Damaging young stems.
  • Tearing young leaves under your feet and the mower’s wheels. 

This damage can be avoided by simply postponing mowing until the grass is stronger.

How to mow correctly after overseeding

Weeks have passed, and the new grass is tall enough for the first mow. You’re excited, and it’s natural, but there’s something you must know before mowing your overseeded turf – while most of your turf is established, the young grass in your lawn is still far from that and requires special care when trimming it.

Sharpen the lawn mower blades

Blunt blades can’t make a clean, swift cut and risk tearing the grass blades and pulling weaker seedlings out of the soil. Sharpen the mower blades before making the first cut on overseeded turf.

Walk more carefully

You’ve been waiting to mow the lawn for weeks, so don’t rush it. Enjoy the feeling of your newly seeded thick, green lawn, and drive the mower carefully. Walk a bit slower than usual and pay extra attention when turning the mower around — that’s when grass blades can get caught on the mower.

Stay with a basic mowing pattern

Making art on your lawn with newly planted grass is like racing your car in traffic with a kid on board — a bad idea! Simply drive your lawn mower back and forth, aiming for the correct mowing height, a steady pace, an even cut, and the least foot impact possible. 

Don’t mow wet grass

when the grass is wet
Photo Credit: Pexels

Cutting wet grass is risky, even with a robust, established turf. With newly sprung seedlings, it’s a recipe for disaster. Wet blades hang on everything, from the mower’s wheels and blades to your shoes. You’ll get torn leaves instead of clean cuts and lots of freshly grown turf pulled from the roots. 

Not to mention that cutting wet turf increases the risk of fungal infections.

Mow when it is cool outside

Freshly cut grass loses water faster and has fewer resources to face the heat. Plan your mowing sessions when the weather is mild, and avoid the scorching mid-day sun.

Don’t cut more than ⅓ of the blade

You’ve waited a while, so the lawn might be taller than you like. Don’t cut more than ⅓ of the grass length — it’s a basic mowing rule that protects the grass’s health. Use more mowing seasons to get it to its regular height safely. When you cut too much from a grass plant:

  • It can’t heal as fast
  • Some tips dry out and take a straw color
  • The plant is more exposed to diseases

What about the grass clippings?

Opinions vary on bagging vs. mulching the clippings after overseeding. Some say leave the grass clippings on the lawn to feed the new grass, while others say it might hinder new growth. 

Decide for yourself depending on what your lawn looks like and the weather:

  • If drought and hot, grass clippings can help keep some moisture in the soil and protect the roots, especially on a thinned lawn. 
  • Conversely, collecting grass clippings can give seedlings better sun exposure if it is cloudy and rainy or on a shady lawn.

Lawn care tips after overseeding

It’s not only mowing that can make or break your lawn after overseeding. Your newly broadcasted seeds require proper care to develop into the sturdy turf you love and plan for. 

Keep the topsoil moist

sprinkler on and sitting in a yard
Photo Credit: Unsplash

Focus on the top 2 inches of your lawn until the seed germinates. Irrigate two times a day in short sessions of 5 to 10 minutes. Depending on the species, it typically takes 10 to 14 days for grass to germinate. 

Remember your established grass. Give it deep watering once weekly to moisten 6 to 8 inches down and support deep roots.

Once you can see seedlings growing all over the lawn, gradually reduce the watering frequency and return to the regular lawn irrigation schedule.

Avoid stepping on the lawn

Keep foot traffic off the overseeded areas for about a month or at least until you mow for the first time. This includes pets and children playing, installing outdoor furniture for leisure moments, or simply using the area as a path to cross the lawn. 

Apply fertilizer at least one month after overseeding

person rertilizing lawn
Photo Credit: Adobe Stock

“Approximately six weeks after germination, fertilize the lawn by applying 1 pound of actual nitrogen per 1,000 square feet,” recommends Richard Jauron and Aaron Steil from Iowa State University.

When you overseed, you typically spread a starter fertilizer before or after broadcasting the seeds. That provides nutrients for both new and old grass for a while, and you shouldn’t fertilize for four to six weeks after overseeding. If you fertilize too soon, mature grass might grow too quickly and disturb the new plants. 

Delay the use of weed killers

Newly planted grass is more vulnerable to chemical herbicides and homemade weed killers. Therefore, postpone the use of weed killers for two to three months after overseeding. 

The University of Georgia says, “A general rule is to apply a postemergence herbicide at half the recommended rate after three to four mowings. Delaying the postemergence treatment allows the turfgrass seedlings to become established and improves their tolerance to herbicides.” 

FAQ on the first mowing after overseeding

When it’s the best time to overseed your lawn?

The best time to overseed your lawn is late summer to early fall if you’re spreading cool-season grasses and late spring to early summer if you plant Bermudagrass, Zoysia, or other warm-season grasses.

Should you mow before or after aeration?

Mow the lawn 1.5 to 2 inches tall before you aerate the soil and spread new grass seed.

What is the best time of day to overseed?

As for many lawn care tasks, morning is also the best time to overseed a lawn. Wait for a warm but not hot day so the soil reaches the proper germination temperature without drying out the seeds.

Leave the mowing to the pros!

If done right, overseeding can transform a tired, patchy lawn into a dense green turf and the envy of the neighborhood. The best part is that you don’t have to master overseeding to enjoy its benefits. Simply hire a pro to reseed and mow the lawn for you. With Lawn Love, the best lawn care companies are only a click away!

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Main Photo Credit: Adobe Stock

Sinziana Spiridon

Sinziana Spiridon is an outdoorsy blog writer with a green thumb and a passion for organic gardening. When not writing about weeds, pests, soil, and growing plants, she's tending to her veggie garden and the lovely turf strip in her front yard.