When to Cut Grass After Overseeding?


Unsure about how long you have to wait before you can cut your grass after overseeding? More often than not, you get a patchy lawn and opt to restore it by overseeding. If you do it well, you get thick, fast-growing grass in no time. But the question is, how long do you have to wait before you can trim mow it?

Generally, you should wait two to three weeks before cutting your overseeded grass. This duration allows the fragile roots of your new seedlings to settle in the soil. Although, this timeline depends on several factors, such as the type of grass you are planting.

The type of grass you plant will indeed affect the mowing height. And every kind of grass takes a different amount of time to reach the perfect height for mowing. Therefore, you need to know the ideal height for your lawn before you begin mowing. The rule of thumb is that you should never cut more than a third of the length of your grass blade.

This article will help you understand various overseeding concepts from how to do it, when to mow your overseeded lawn, and how to maintain it.


How to Overseed Your Lawn?

Sometimes, your lawn won’t look great due to thinning grass. When this happens, you want to overseed to grow more grass seeds and restore your turf’s lost glory. Besides filling the gaps left with dead grass, overseeding helps treat the remaining grass from pests and various plant diseases.

Overseeding may demand that you adjust some gardening practices, like how and when to mow the lawn. So, here is how to tackle the entire process.


Step One: Mow the Grass

Before you begin overseeding, mow the existing grass. Doing so ensures that you bring the grass height significantly lower to provide enough room for the new seedlings to grow.

Besides, the existing grass still requires its share of nutrients and water, so it would be an excellent idea to trim it. Mowing at this stage also reduces the canopies that may form shade and block sunlight for the new seedlings.

You may also need to rake the lawn to eliminate any dead grasses, sticks, rocks, and other debris. The process is necessary to remove any final barrier that may prevent the grass seed from getting to the soil. It also loosens the soil particles in preparation for seeding and the penetration of young, fragile seedling roots.

You can also choose to amend the soil at this stage. Soil amendment is very different from adding fertilizers because in this case, you have a specific target. For example, you can always add lime, poultry manure, or wood ash to raise the pH value of acidic soil. On the other hand, you can use sulfur to boost the acidity of alkaline soil.


Step Two: Overseed

Overseeding is as simple as choosing the type of grass you want and spreading it onto your yards. The unique detail here is that you are doing it more than usual across the parts, which you want to flourish more in the spring.

Load the grass seeds you want to use into a seed spreader, then spread around 16 seeds for each square inch of soil. Note that this density may depend on the thickness of the existing grass and that some lawns may need less or even more. You can also spread the seeds by hand (especially in smaller areas), although it takes longer and demands more energy.

When choosing the grass seeds, go for the species designed for your specific climate or region. You also want to pick one that complements the existing lawn.

Plus, your project will yield even better results if you overseed and aerate at the same time.


Step Three: Apply Fertilizer

Make sure to select the best fertilizer for this purpose, then load it into a fertilizer spreader. After that, scatter it around the perimeter of the space. Doing so ensures that the fertilizer reaches the edges.

After exhausting the edges, follow a pattern similar to mowing, moving the spreader in a straight row at a time.

There are different fertilizers for this purpose, including handled, broadcaster, drop, and snap spreaders. Of course, you can always pick one based on the yard size and type of fertilizer.

For example, broadcast spreaders are ideal for larger yards, while you may use a handheld spreader in small-sized yards. Similarly, liquid fertilizers will require liquid fertilizer spreaders.


Step Four: Water Your Lawn

Your seeds need plenty of water to germinate and thrive afterward. Therefore, the watering process should begin on day one — when you overseed — and last until the third day. During this period, your yard will need more water than it normally will throughout the year.

You may opt to water the surface once or twice a day depending on the weather. While doing so, make sure to saturate the overseeded regions with enough water to keep the upper 1/4 of the soil moist. After three days, return to your regular watering schedule.


Step Five: Mow

Mowing causes a lot of stress to the plants. Therefore, it is best to give it enough time to settle before trimming them to size.

After overseeding, aerating, and watering, wait two to three weeks before mowing the grass. As said before, the waiting period varies based on multiple factors, such as the type of grass in your yard and your location.

Each type of grass has a unique germinating speed. For instance, Ryegrass and Fescue take about 10 to 14 days to germinate, while Kentucky bluegrass is a bit slower to grow and takes up to four weeks to germinate. Thus, you should consider this before mowing.


How to Cut Grass After Overseeding?

The type of grass you grow will also determine how fast it reaches the mowable length. If you can’t figure out the exact length of your grass, just go for the rule of thumb, which consists of never chopping more than a third of the existing blade length at any mowing session.

Because of this, you should know the ideal height you want your turf to reach. Once you determine this, allow it to grow more than one-third that long before mowing it.


Why Is Overseeding Important?

Overseeding is a crucial part of the lawn care regime. It involves sowing grass seeds in an existing lawn. Among several reasons why you might want to do this is that it:


Gives You a Dense, Lush Lawn

No one fancies a dull, thin, and patchy lawn. Besides looking unhealthy, such lawns provide space for weeds and moss to grow. Weeds naturally love to concur, so they will occupy the entire space, eliminating every trace of grass with time.

Overseeding helps prevent this from happening. It restores the lawn, forming a dense cover of thick, green, and healthier-looking grass. Overseeding also crowds out any weeds and moss, depriving them of the suitable conditions they need to thrive.


Helps Your Lawn Recover After an Invasive Treatment

Lawn care and maintenance practices require that you periodically rake, aerate, and scarify the grass. Doing so removes the thatch and moss, relieves the soil compactions, and improves the drainage and airflow within the lawn.

On the flip side, it is often an invasive process that leaves your grass scattered and the lawn worse than it originally was. You can always overseed your grass after scarifying and aerating it to restore its beauty and improve its density.


Reduces the Risk of Grass Pests and Diseases

Besides using pesticides and other chemicals, you can combat pests and diseases by maintaining a healthy lawn. You can either achieve this by regularly watering your grass or by overseeding the lawn. With the latter, you must consider the seed type based on its unique benefits.

With this, you have to select seeds that thrive in your area as they will provide better disease resistance and demand less water and other maintenance practices. In addition, growing healthier lawns means that you will spend less money on pesticides since you won’t have to worry about pests and diseases.


Improves Your Lawn’s Appearance

Overseeding improves your lawn’s appearance or tolerance in various ways. For instance, if you have an ornament that can’t withstand people walking or kids playing on it, you can overseed and mix it with a more tolerant species. This improves its quality and helps it manage stress without losing its beauty.

Similarly, the grass might be sparse and patchy in a few areas of your lawn. It may be because the grass is not so hardy to grow in that section. In that case, overseed with a hardier and tolerant species that will withstand that situation.


Reduces Erosion

Most grasses, if not all, have compact, fibrous root systems that bind together. By overseeding, you increase the bindings and the density, limiting the space between each grass. In addition, densely planted grass blocks water run-off, keeping soil and water on the upper part of the slope. As a result, you can limit the soil loss and perfect the nutrient level in your compound.


Can You Use Too Much Grass Seed When Overseeding?

As you plan to overseed your lawn, you must understand that using too many grass seeds won’t offer you a lusher lawn. Instead, it may make your grass struggle and, to the extreme, completely fail the project.

Here are some of the issues that putting too many grass seeds will do to your lawn.


Reduce the Germination Rate

The first obvious issue with putting too many grass seeds is that it will decrease the rate at which the seeds germinate.

When you put the seeds down, it is survival for the fittest. Every seed wants a share of the soil and nutrients to germinate. Unfortunately, their excess number means that every seed struggles to access water, ideal temperatures, and oxygen, the three most necessary factors that aid germination.

Most seeds will only get enough factors to survive with such completion but will not grow as fast as they should. Typically, grass seeds may take about one to three weeks to germinate. However, throwing too many of them in the soil may extend this period.


Slow Down the Growth Rate

Even when the seeds germinate, they still have to compete for these limited resources. Plants require enough space in the soil to establish their roots. However, spreading too many grass seeds encourages root competition between the individual seedlings as they attempt to grow.

With that, some seedlings will push through the soil quickly and absorb the limited moisture and nutrients before others get to that stage.

Also, some seedlings will barely get their roots to the soil, thus being deprived of the necessary amount of nutrients. As a result, they will not have healthy stalks and may die sooner or later. Overseeding may leave you with a patchy-looking lawn from the mixture of healthy and unhealthy grass.


How to Calculate the Right Amount of Grass Seeds for Overseeding?

With all the potential disadvantages of throwing an excessive amount of grass in the yard, you must get the measurements right, as neither excess nor a lack of grass seeds is optimal. With that in mind, how much is enough?

Here is how to determine the right amount of grass for overseeding.


Step One: Measure Your Lawn

Most commercially available grass seeds come with instructions on the packaging. You can always go through these to get the manufacturer’s recommendations.

The instructions will most of the time tell you how to sow the grass rather than the amount of seeds you should use. The right amount of grass seeds you need to get a full green lawn depends on the type of grass you buy for the overseeding project and the size of the area you want to cover.

The best way to approach this is to measure the area in feet. You can do so by multiplying the length of the lawn by its width if it is square or rectangular. Then, take away any non-lawn spaces, such as patios, paths, and decks. This will leave you with the total square footage of the lawn you want to cover.

If the lawn area has an irregular shape without four approximate edges, subdivide it into smaller rectangles or squares, then measure every small area’s width and length.


Step Two: Find the Area to Overseed

Then, multiply them separately and find the total. The result will give the approximate area you need to cover. If it comes to smaller decimals or numbers, round up the number to the next 10 or 100 for a simplified calculation.

Seeding rates are generally available in pounds per 1,000 square feet. So, divide the figure you find in the step above by 1,000 to get the number of your 100-foot sections. For smaller lawns, the result may be in decimal below 1.


Step Three: Choose Your Grass Species

Several factors will determine the type of grass you pick. However, we recommend you first choose the grass species that matches the existing species on your lawn. Doing this ensures that you get a uniform, beautiful lawn without patches of mixed colors.

For example, if you want to overseed a thinning yet healthy lawn, go for the same grass species and the same characteristics.

You may also want to introduce a winter color in your yard if this is the case for cool-season grass like bentgrass, bluegrass, or ryegrass.


Step Four: Find the Seeding Rate

After identifying the type of grass seed you want to plant, multiply the decimal you previously calculated by the seeding rate in the grass species. The rate may vary depending on the species. For instance, colonial and creeping bentgrasses have a seeding rate of about .5 to 1 lb. for every 1,000 square feet.


What Is the Best Time to Overseed?

The first and most important thing in overseeding is getting the season right. For cool-season grasses in the northern region, the best planting period is early in the fall. At this time of the year, the grass is thriving thanks to the warm soil.

Meanwhile, stubborn, warm-season lawn weeds, like nutsedge and crabgrass, are less active during this time, meaning your seedlings will have less competition. For best results, overseed at least 45 days before the first fall frost.

Warm-season grass in southern areas tends to enter active growth late in the spring, making it the best time to overseed. However, you can also do it in early summer as soil temperatures get warm enough for the seeds to develop.

The Pacific Northwest is ideal for cool-season grasses, while the North West is ideal for warm-season grasses. For best results in these regions, overseed cool-season seed grasses about six weeks before winter and warm-season grass seeds in early spring. For the Midwest region, it is best to plant your cool grass seeds between mid-August and Mid-September.


Bottom Line

Overseeding is part of routine lawn maintenance practices. However, you must get every step right. You must know when to do it, when to mow the lawn, and the type of grass to use. Failure to get this right may cause further damages to your grass and leave you with regrets.

After reading this article, we believe you have the proper skills and knowledge to overseed your grass.

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