How To Kill Bermuda Grass In St. Augustine Lawn?

Remove Bermuda Grass In St. Augustine Lawn

Are you having problems with Bermuda grass taking over your St. Augustine lawn?

Well, before you go about bringing out your cans of herbicides and start spraying it all over the area, there are a few things that you need to know about this hardy, and some would even say stubborn grass.

Bermuda, which is a very invasive type of grass can actually spread its seeds when you are out mowing your lawn. It can also spread underground through a hard-to-remove root system called rhizomes.

And, as if that wasn’t enough, it can even expand above the ground via “runners” called a stolon.

So, it seems like the only way you can get rid of this grass is to do a resod, and sometimes that may not even be enough as the Bermuda roots can grow up to 6 feet underground, making it hard to do a complete removal.

Not to worry, there are a few effective ways we can get rid of this type of grass. You can restore the beauty of your lawn the way that you would want, well-manicured, and with some consistent height made of lush green color.

Although Bermuda and St Augustine grasses are similar warm-season grass varieties they are different. There are several ways to kill Bermuda grass and stop it invading without harming your st Augustine. The best ways don’t use any chemicals but do require a large amount of patience.

How to Control Invading Bermudagrass in St. Augustine Grass

Check out my full ultimate guide to St Augustine grass.

How to Kill Bermuda Grass in St Augustine Lawn?


This method involves using direct sunlight and heat to kill off the grass. This is usually done in summer when it is hot and dry.


  • Prepare Bermuda by mowing it and making it short enough for easy removal.
  • Cover the patch with large clear plastic sheets over where there are patches of Bermuda. Make sure that the plastic sheets are securely placed and held down to the ground with some stones and heavy sticks every few meters or so.
  • Keep the plot covered for at least a month or more, to completely “burn” and dry out Bermuda.

Choking Out the Weeds

This method is the exact reverse of solarization in which you will deprive the grass of sunlight and air. Bermuda doesn’t thrive in well-shaded areas and this smothering method will accelerate wilting and browning.


  • Cover the spot with compost.
  • Use two flattened out cardboard boxes as boards to cover the area and make sure they are held down securely to the ground.
  • Wet the cardboard and cover it with mulched material.
  • Allow at least 3 months for the grass to completely die off.

Change Your Mowing Height

Bermuda grass does not grow so well in the shade so if you set your mower to its highest cutting height and cut it to that height for several months you should see a reduction in the amount of Bermuda.

The test is how many months do you want to keep your lawn at maximum height? the longer you keep it long the more you will reduce or kill the bermuda grass.

Check out my article on the best push reel mowers.

Selective Herbicide Treatment (for partial infestation)

If your lawn hasn’t been fully invaded yet, you can use a good brand of herbicide that is specified to kill Bermuda grass only.

Always remember to use protective equipment and follow instructions exactly as it is indicated on the label. After treatment remove dead debris and make sure to remove all of the roots too.

Non-Selective Herbicide Treatment and Resodding (heavy infestation)


  • Use a non-selective herbicide that will kill Bermuda (as well as some of the surrounding St. Augustine) from where it has grown. This will depend on how much it has already invaded the yard. Spray according to instructions on the label.
  • After killing Bermuda with herbicide remove the dead grass and rake or scarify your lawn to make sure you remove all the remaining roots otherwise it will eventually grow back. In the case of having to treat the whole yard, remove all the dead grass, sod cut, and clean out the grass runners.
  • Apply fertilizer to allow quick recovery of the soil.
  • Resod and install St. Augustine grass in areas where desired.
Bermudagrass vs. St. Augustine Grass // Which Warm Season Turf is Right for Your Lawn?

Is Bermuda or St. Augustine Grass Better?

We will be making a comparison on both types of grass according to the following conditions as well as based on their strengths and adaptability.

Climate Tolerance

Both types of grass go into a dormant mode during the winter months. However, St Agustine seems to do better with extreme weather changes.

Water Needs

Bermuda can do well with less amount of water compared to St. Augustine.

Soil Needs

Bermuda grass has a significantly higher fertilizer requirement compared to St. Augustine’s. It needs more nitrogen and doesn’t need as much of other elements. It is safe to say that Bermuda could be a little bit more expensive in terms of maintenance and care.


Bermuda cannot thrive under shade compared to St Augustine that can handle it well.

Resiliency to Traffic

St. Augustine comes second to Bermuda when it comes to traffic. Bermuda holds better when played or trampled on.

Conclusively, when it comes to ease of maintenance and adaptability St. Augustine is definitely a better choice.

On the other hand, if you are looking for grass that is sturdy and can withstand some trampling by your kids and stay alive after that Bermuda is a great choice. You will just have to contend with the additional care that it needs, plus it doesn’t handle shade very well.

Check out my full ultimate guide to Bermuda grass.

Can You Mix St. Augustine with Bermuda?

Yes. However, there are a few things that I did in my backyard to make sure that Bermuda doesn’t overrun the St. Augustine. I set my mower to the highest setting, this way St. Aug still dominated and created a shade that will keep Bermuda in check.

I water the grass weekly to keep St Augustine green and alive. The idea is that as long the St. Augustine is thriving from adequate irrigation, Bermuda cannot step in to occupy the space.

Also, Bermuda likes fertilizers more than St. Augustine, so I make it to a point to fertilize only three times a year. This way I can provide nutrition suited to St. Augustine.

Check out my article on the best sprinkler systems to grow a healthy lawn.

How Fast Does Bermuda Grass Spread?

Bermuda is known as a perennial warm-season grass. It thrives during the hot summer months and its qualities are, being resistant to heat, traffic, and tolerance to salt. It can even survive a period of drought.

Bermuda is known to have the fastest growth rate among all other warm-season grasses. Depending on how you mow it, it can go vertical on a high setting cut, and it can grow horizontal on a regular low setting cut.

It also grows quickly underground. It takes only 14-21 days to germinate and grow.

Because of the various ways it grows, it can spread quickly too. Using a mower can cause its seeds to be thrown outwards and germinate somewhere else. If the roots are not totally removed when cultivating the soil, it can grow even from one tiny piece that was not killed or removed.

Will Bermuda Grass Take Over St. Augustine?

Given the chance, it will. It is important to recognize how Bermuda propagates itself and learn the steps on how to minimize it, and if possible, stop it altogether.

The information contained above will likely solve the problem since all you have to do is take care to be thorough and diligent. This way, you won’t have to worry about having to go back and redo the prevention steps as described.

Check out my full bermuda v st augustine article.

Shade Tolerance of St. Augustine Compared to Bermuda Grass

St. Augustine, being one of the best options for home and commercial lawns, comes out as a clear winner when it comes to shade tolerance. It is one of the most popular grasses of choice for lawns throughout the United States.

It grows best in sandy soil with a PH that ranges from 5.0 to 8.5.

The best cultivar of this type of grass is Seville, Sapphire, Bitter Blue, and Palmetto. It doesn’t only do well in the shade it also flourishes under direct sunlight. They can even live on only five to six hours of sunlight a day.

The purpose of cutting St. Augustine in a high setting is for the blades to absorb more sunlight and more of that ultraviolet energy it needs.

On the other hand, Bermuda which has a poor tolerance for shade, simply cannot thrive with no sun.

Check out my article on the different varieties of St Augustine grass.

Mow Your Lawn To the Highest Setting (Bermuda likes low setting)

St. Augustine is a medium maintenance grass that looks pretty and to some extent a hardy grass. Below are the seasons and suggested mowing heights that work well for this type of grass.

St. Augustine Spring and Summer Months Mowing Height

The suggested grass height is 2.5 inches to 3.5 inches. Allow a notch shorter when mowing in March to clean out debris. For lawns with more shade, make it 3 inches to 3.5 inches in height. Mow at least once a week.

St Augustine Fall Mowing Height

Make it 3 to 3.5 inches maintained up until winter.

Bermuda Spring and Summer Months Mowing Height

Mow in March at 2 notches shorter.

The suggested grass height is 1.5 inches to 2.5 inches, while slowly raising the height when approaching hotter weather. Mow every 7 days to maintain and protect your lawn.

Bermuda Fall Mowing Height

Maintain 2 inches height up until winter comes.

How Do I Permanently Kill Bermuda Grass?

Apart from what was mentioned before, one of the most effective ways of permanently killing Bermuda grass is Solarization.

It is worth mentioning since it is also the easiest way to do it.

Just set it up and wait for 4 weeks. After it bakes the soil and kills the grass just remove the plastic wrap and rake off the dead grass or you can leave it there to decompose.

However toxic it might be, using a herbicide is also a permanent way of killing off Bermuda grass. The downside to it is chemicals may have some long term effects on the health of your soil.

And last but not the least, Mulching. This method can also be a great way of permanently eradicating Bermuda grass. In the process of killing it, mulching also enriches the soil for the next resod.


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