How To Overseed a Lawn For Optimum Results

If your lawn is looking patchy and thin and you might be wondering if overseeding is the solution. Today we will teach you how to overseed your lawn follow it up with some tips and pointers to give you the lush lawn you’re hoping for.

How to overseed a lawn for amazing results.

Overseeding your lawn is a great way to improve the current density of your grass as well as improve the varieties of grass in your lawn.  When overseeding is done right with the proper preparation you can have a full lawn within a month or so depending on the variety of grass you choose.  

The Backyard Master

How Do You Overseed A Lawn?

This first thing to consider when overseeding is if it is appropriate for you and your lawn. 

If your lawn currently has at least 50% coverage of your desired grass type, then you (and your lawn) would be a candidates for overseeding. 

However, if your lawn is less than 50% desirable grass or is overtaken by weeds it might be better to kill off or remove your existing grass and start over.  For the purpose of this guide we will focus on the overseeding process.

The second thing to determine is what type(s) of grass are currently growing in your lawn? 

Let’s start by looking at cool season lawns. When you’re working on creating a great looking lawn, it is important to try and maintain a consistent mixture for a more uniform look and a more consistent growth pattern. 

Overseeding Cool Season Lawns

With that said, many lawns will have a mixture of various cool season grass such as Perennial Ryegrass (PRG), Turf Type Tall Fescue (TTTF), or Kentucky Bluegrass (KGB) and that’s okay.  These varieties are common in cool season zones as well as the transition zone. 

Upon closer inspection of your lawn, if you notice it consists of a single variety such as Perennial Ryegrass or Turf Type Tall Fescue, overseeding is appropriate. 

If your lawn is a mixture of any of the three cool season grasses mentioned above it is also a good candidate for over seeding.  Lawns that consist of primarily Perennial Ryegrass or Turf Type Tall Fescue need overseeing every couple of years or when the yard is looking thin. 

These grass types are classified as “bunch” grasses and will not fill-in spots where grass has died due to summer stress or drought.  Some lawns are overseeded every season which is common practice in sports turf.  If your lawn looks poor and stressed coming out of summer overseeding is recommended. 

A lawn composed of only Kentucky Bluegrass can spread rather quickly with frequent fertilizer applications in the spring and fall and may not require overseeding. 

If you choose to overseed your Kentucky Bluegrass lawn it is best to stick with KBG seed for the process as it will promote uniformity. 

Overseeding with KBG can be a more challenging process due to the slow germination rate of the seed which is anywhere from 14-28days.  By the time the seed germinates, the established grass will need to be mowed or it will potentially shade out the new seedlings and starve them from light causing them to die off. 

It is more ideal if there are larger areas that are completely bare since these areas can be seeded with Kentucky Bluegrass and there won’t be any existing grass to compete with the seedlings.  To properly seed these areas you can follow our steps that are highlighted below.

Overseeding Warm Season Lawns

Overseeding warm season turfs such as Bermuda, Zoysia and St. Augustine is not recommended as these turf types are extremely vigorous and will spread rapidly with adequate fertilization during the warm summer months. 

Many of these popular varieties are also non seeded varieties and can only be laid as sod, sprigs or plugs as they do not have vegetative seed. 

However, if your lawn was indeed seeded and you have large open areas that are bare you can reseed with the same variety that was used before.  It is important to use the same seed that was used previously as it will match your existing turf in color and growth rates. 

For seeding these bare spots in warm season lawns you can follow our steps below.  It is important to seed warm season grasses when soil temperatures are at least 65-70 degrees to allow for good germination.

When Is The Best Time to Overseed?

Once you have determined if you need to overseeding is the best way to go and have purchased your seeds it is time to plan and prep for your project. 

The best time to overseed cool season lawns is going to be in the early fall about 60-75 days before your traditional first date of frost and in the beginning of summer for warm season lawns.

Fall overseeding is generally better for cool season lawns as there is less weed pressure and soil temperatures are warmer and will help with germination.  Seeding in the fall will also give your new grass longer to develop and mature going into the following spring and summer to enable it to withstand warmer temperatures and potential drought.  

If you are seeding in the spring you will want to wait until soil temperatures are at least averaging 50-55 degrees which is the minimum at which seeds will germinate.  With spring seeding it is important to water at least 1 inch weekly in the summer to ensure your new grass thrives.  

How To Prep Your Lawn For Overseeding

After you have determined your overseeding time it’s time to do your prep work. 

The first step is mow your lawn shorter. 

In this scenario it is ok to scalp as your lawn will recover. 

  • Lower the blades on your mower as low as you can without consistently hitting dirt. While you are mowing it is important to bag and catch your clippings to help remove as much debris and clippings as possible. 
  • Repeat this process 2-3 three times in different directions.  This is achieved by mowing north to south, east to west and finally at a diagonal.  
  • Ensure good seed to soil contact by “roughing up” the ground using a rake or mechanical dethatcher. By doing this the ground will be more acceptable for seeds and you will also remove any dead material from your lawn.  Whether you use a manual rake or a mechanical dethatcher, you want to mow again to help clean-up any of the dead material that was pulled to the surface.
  • Next you should aerate you lawn. Aeration will also provide a good soil bed for seeds to germinate, similar to dethatching.

This process is best done with a mechanical aeration machine that can be rented at local tool rental centers and most home improvement stores.  This machine will pull cores from your lawn leaving small holes that will help relieve compaction and provide a nice spot for some of your seeds to fall during seeding.  

After you have pulled your cores you can leave them in the lawn and mow/mulch them with your lawn mower without the bag. They will decompose rather quickly into your soil and help to provide a good seedbed.   This process is not always necessary when overseeding but if performed it can increase the seed to soil contact and increase the germination rate.

  • Weed control before overseeding is also important.  If these weeds are not taken care of now they will have the opportunity to be there in the future. 

You can hand pull as many weeds as possible or you can dig them out with a spaded shovel. 
If the weeds in your lawn are abundant and overwhelming you can spot spray areas with Round Up (glyphosate). 

This is a good method because it will kill the weed and it is safe to use all the way up to the time of seeding. 

There are other weed control products available to use but it is important to read the label and follow the seeding guidelines listed.  Many of these products need to be applied between 2 to 4 weeks before seeding so plan accordingly.

The preparation before you plant your seeds is the most important aspect of overseeding your lawn to achieve the best results.  I

t’s important to give yourself plenty of time to get these steps done over the course of a couple of days or consecutive weekends. 

Don’t skimp on the prep work it will pay off.

How Much Seed Will You Need?

Now you’re finally ready to plant your seed! 

The amount of seed that you will use will depend on the type of seed you have picked. 

Seeding rates are based on 1,000 square feet intervals so it is important to know the size of your lawn.  To do this you want to measure the length and the width and multiply those numbers together to obtain your square footage. 

For example, a lawn with a length of 40 feet multiplied by its width of 50 feet will give you a measurement of 2,000 square feet. 

Now that you have determined the size of your lawn let’s figure out how much seed you need. 

As mentioned before seeding rates will vary depending on which grass type you are using.  Our recommended rates by seed type are listed below. 

Note more seed is not necessarily better as the seedlings will compete for nutrients and will ultimately lead to overcrowding and poor germination.

Turf Type Tall Fescue 10 lbs per 1,000 sq ft
Perennial Ryegrass10-15 lbs per 1,000 sq ft
Kentucky Bluegrass2-3 lbs per 1,000 sq ft
Bermuda2-3 lbs per 1,000 sq ft
Recommended Rates By Seed Type @ The Backyard Master

Using our example of the 2,000 square foot lawn, you would want to use about 20lbs of Tall Fescue to overseed your existing lawn. 

If using Perennial Ryegrass you would use somewhere between 20-30lbs of seed. 

Lastly if you were overseeding with Kentucky Bluegrass you would use between 4 and 6 pounds of seed. 

The difference in seeding rates are due to the size of the seed. 10 pounds of Tall Fescue and about 2 pounds of Kentucky Bluegrass will have about the same number of seeds as Kentucky Bluegrass seed is much smaller.

How to Apply Your Seed for Success

We’ve determined how much seed to use so now it’s time to plant your seed. 

The easiest way to spread your seeds on your lawn is with a drop or rotary spreader that you would use to apply fertilizer to your lawn. 

You want to place the spreader setting on the lowest setting that will allow the seed to go through the holes. 

Your going to make multiple passes ideally north to south and east to west to ensure even coverage with your new seed. 

For smaller lawns you can plant by hand.  To perform this method you can grab a handful of seeds and gently shake them while walking to disperse the seed.  

How to Care for your Overseeded Lawn

After the seed has been planted it’s time to water. 

It’s important to maintain soil moisture and not allow the seeds to dry out. 

To do this you will want to water 2-4 times a day without creating puddles in the lawn. This is best achieved with watering between 5-10 minutes each time. 

Test this before you plant your seeds. 

You will want to maintain this practice until the new seedlings germinate and the new grass is about an inch in height.  At that time you can back off on your watering and return to your normal watering schedule.

Once your new grass has reached about 3 inches in height it will be time for your first mow. 

When performing your first mow take caution on turns as the new grass is not rooted well and can be easily lifted up. 

At this time we also recommend giving your overseeded lawn a dose of starter fertilizer or a fertilizer with a 1-1-1 ratio of nitrogen, phosphorus and potassium.  Look for products such as a 10-10-10, or a 20-20-20 fertilizer for example.

Once your newly seeded lawn is established it is important to maintain a good mowing schedule to help it thicken up and promote a healthy lawn.

This is best performed by following the 1/3 rule and never removing more than ⅓ of the leaf blade in a single cutting. 

Overseeding FAQ’s

Can you overseed your lawn without aerating?

Yes, you can overseed without aerating your lawn.  At a minimum you need to rake your lawn and remove as much dead material as you can.  This will ultimately provide a good spot for seeds to meet the soil and improve results.

Can you overseed a lawn with weeds?

Overseeding a lawn that is full of weeds is not recommended.  Weeds will compete with grass and newly sprouted seeds for sunlight and soil nutrients.  It is best to remove or kill as many weeds in the lawn before overseeding. 

Does overseeding your lawn really work?

Overseeding your lawn will yield great results with the proper preparation.  It is important to provide the best environment for your grass seeds to develop.  This is done by mowing your current grass low, aerating/dethatching, planting and watering.

How often should you overseed a lawn?

Depending on the condition of your lawn you can overseed every few seasons to increase the density and aesthetics of your lawn.  If you live in an area where heat and drought stress occurs during the summer you may need to overseed every fall.

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