When To Mow After Overseeding- Days Or Weeks?

When it comes to mowing your lawn, timing is crucial. Haphazardly cutting your grass can have adverse effects on its development and, ultimately, your goal of a lush and glorious lawn. 

A lawn should be mowed 2 – 4 weeks after overseeding as long as the new grass blades pass the ‘pull test’, have been watered regularly, and have rooted in quality soil. If it is done sooner mowing could cause stress to new grass and later could risk a clippings pile up and an uneven cut.

Today we take a look at the importance of timing your mows after you overseed your lawn. Join in, as we discuss the best periods to tackle various grass seedlings, as well as the best mowing techniques you can use for the best results. Let’s go.


Can You Mow After Overseeding?

It may not be obvious to some that mowing is essential for healthy grass growth. Too much height can cause newer blades to be shaded and the new plants to die out.

Not only can you mow after overseeding, but you should mow. The sticking point is when it should be done, at what height, and the amount of wear and tear your mower will cause in the process. It is also important to consider if your new grass has been properly irrigated.

It is essential to follow some simple guidelines when doing the first mow on newly grown grass. Read on and I will detail all you need to know to help your grass grow green and full.

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How Soon Can You Cut Your Grass After Overseeding?

So, you’re trying to repair the many bare patches on your current lawn. Or, perhaps, you feel your lawn needs rejuvenation after enduring several seasons. Unless you are prepared to rip it all up and lay down new turf from scratch, aeration and overseeding are the way to go.

Generally speaking, you should wait anywhere between 2 and 4 weeks from the time you overseed to the first mow. This is the typical range for most lawn grass species. Both cool and warm season grasses should be cut between 2 and 4 inches depending on the type.

However, the fact that overseeding is the “easier” of the two solutions doesn’t mean that you must neglect proper management. 

The timing of your mows is one of the key aspects to succeeding at overseeding. Too soon, and you risk stressing out your fledgling grass shoots. Too late, and you will be forced to spend additional time cutting the unkept grass.

Of course, the specific timing will depend on several factors, chief among which is the height of the grass seedlings. As you probably know, different species of grass grow at different rates. Additionally, grasses have different peak growth seasons.

In the U.S., we have two classes of lawn grass: cool-season and warm-season.

Warm-season grasses (St. Augustine, Bermuda, etc.) experience peak growth from late spring through summer while cool grasses (Kentucky Bluegrass, Perennial ryegrass) grow the fastest in early spring and the fall.

Another factor that impacts the growth rate of your grass is the soil conditions. Nutrient-rich soil will, more often than not, stimulate faster growth, which will allow you to mow earlier.

Sunlight is yet another major factor. The longer your grass shoots are exposed to direct sunshine, the faster they will grow. This is why we recommend that you avoid overseeding during the winter months when the days are short.

Below is a pair of tables indicating the best cutting heights for various species of overseeded lawn grass.

Cool-season Grasses

After overseeding cool-season grasses it is important to get the proper height on your lawn so that the new blades are not damaged or roots are not pulled up. It is also important to use a sharpened mower blade so a clean cut is achieved.

SpeciesRecommended cutting height
Tall Fescue2-4 inches
Fine Fescue2-4 inches
Perennial ryegrass1-3 inches
Kentucky Blue1-4 inches

Though these taller sometimes greener yard grasses can create a wonderfully healthy and plush lawn, they do need quite a bit of TLC to get there. Making sure that new blades are not cut too close is an essential part of the process.

Warm-season grasses

Though warm season grasses tend to be a be hardier and on average can be cut lower, the same issues still apply. Use a sharp mower blade and set the mower to the proper height for your new grass.

SpeciesRecommended cutting height
Buffalo grass2-4 inches
Zoysia1-3 inches
St. Augustine1-3 inches
Centipede grass1-3 inches
Kikuyu1-2 inches
Bahia3-4 inches
Bermuda3-4 inches

These grasses tend to be a bit hardier, but during the colder months they tend to be less green. This doesn’t take away from their usefulness though, since they tend to be thicker and more even most of the year if conditions are right.

The Pull Test After Overseeding

Another good sign that your new seedlings are ready for mowing is the “pull test”.

Basically, you pull on the shoots slightly and gauge the resistance. The aim of this is to determine whether the new grass has taken root sufficiently enough to be mowed.

Adequate Watering Is Necessary Before Mowing After Overseeding

Another major factor that may require you to delay the first mow is your watering. 

One of the trickiest issues with overseeding is the fact that matured grass requires much more water than emerging shoots. In fact, too much water will delay grass seedlings’ acclimatization process. Grass seed and seedlings require only a tiny bit of moisture, but you may be forced to overwater to sustain the existing grass.

To read more about the grass in your lawn, see my other articles…

Should I Bag My Grass Clippings After Overseeding?

The answer to this question may vary depending on your particular circumstances. Yet, there are some general principles that all can follow.

It is a good idea to bag grass clippings if the problem in your yard that overseeding is addressing is bare patches. If the problems are not localized in a few general areas, clippings shouldn’t be collected. For whole lawn fixes, clippings can actually help the lawn recover faster.

If you’ve overseeded your lawn to fix a few minor patches here and there, it’s better that you bag most of the grass clippings. Mulching or discharging, especially if your grass is thick, may lead to excess clumping, which may stifle the new grass.

Clumped grass may also force you to rake the lawn to distribute the clippings evenly, which may lead to even more stress on the grass.

If you are dealing with serious patching or a ravaging lawn disease, you may be more inclined to mulch your clippings back into the lawn so it can get as many nutrients as possible. I recommend a 50/50 split between mulching and bagging, but feel free to mulch more if you are dealing with very large patches.

How Do You Cut Grass After Overseeding?

After overseeding, your number one priority must always be to minimize stress on the emerging grass. Mowing is one of the most stressful activities for your grass you can engage in, so you should do it right.

After you mow your existing grass short and overseed, wait 2 to 4 weeks before cutting. To make the first cut use light weight equipment, a sharp your mower blade on dry grass, and the highest setting on your mower for your grass type. This should leave cleanly cut, healthy grass blades.

But firstly, let’s take a look at what you should do before you overseed.

Before planting new grass seed, you must mow the existing grass as short as possible. This helps you get rid of excessively tall grass and weeds that would otherwise compete for resources with the emerging shoots. This initial mowing essentially gives the new grass a competitive leg up.

When the time comes for the first post-overseed mow, we recommend that you take a few precautions.

  1. Firstly, you must try to use a lawnmower that is as light as possible. If you are working on a small or medium-sized yard, we recommend that you use a simple push mower to avoid trampling the young grass. 
  2. Secondly, ensure that your mower blades are sharp. The last thing you want to do is to cut your new grass with dull blades, which tend to tear the grass rather than cut it. If the grass is not cut cleanly, it will be highly susceptible to lawn diseases and pests.
  3. Another thing you must look at before mowing is whether the grass is wet. You must never cut emerging grass while it is wet because you risk undoing the weeks of root establishment. Also, moving a lawnmower over wet shoots may stifle them and affect their development.
  4. Lastly, for the first mow, you want to ensure that you cut the grass as high as possible.  Even if you delay the first mow by an additional couple of weeks, cutting the grass too short will disrupt the establishment of roots.

The grass blades are responsible for catching light required for photosynthesis, which, in turn, grows the grass and its roots. For the first mow, you should not cut more than a third of the total height of the grass blade.

Bonus tip…try to avoid turning the mower on the new grass to save it from strain. If you can, turn the mower on the established grass or a paved surface like your driveway.

The Final Touches On When To Mow After Overseeding…

What we know about grass and lawns is far more advance than a century ago. Today lawn care can be an art and a science rolled into one.

When it comes to mowing new grass it is important to abide by some basic guidelines…

  • Cut your lawn shorter than normal before overseeding to keep down the competition for nutrients for your new plantings.
  • Make sure to water your planted area thoroughly and often to ensure the first mow is cutting green, healthy grass blades.
  • Sharpen your mower blade to prevent it from tearing the new grass blades or uprooting the plants altogether.
  • Allow 2-4 weeks of growing time before attempting your first mow in the area.
  • If you are attempting to revitalize an entire lawn, don’t collect the grass clippings. They can help with the reseeding.
  • If you are tackling only a couple of problem areas, collect grass clippings in order to prevent clumping that can shade new grass from the sun and absorb water.
  • When cutting after overseeding for the first time, avoid using heavy equipment that can pull up or crush new plants and roots.
  • Avoid turning the mower 90 degrees or 180 degrees on the new lawn surface. Turn on existing grass.
  • Cut the grass at the recommended heights, but be sure to use your own judgement. Higher is better in this instance.

Hopefully this has given you something to chew on and will make your overseeding and first cut a satisfying experience.

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Mathew Booe

Mathew has worked in landscaping professionally for over 10 years. He is a grandpa and frequently interviews other experienced landscapers and lawn care experts who are also grandpas for these articles.

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