How to Kill Johnson Grass [All You Need to Know]

Why ruin the look of your beautiful lush green garden because of unwanted Johnson grass sprouting from under your plants?

Many garden enthusiasts complain about their lawns looking distraught because of the unwanted weed outgrowth. Herbicides provide an excellent solution to this problem. Once applied, they attack the roots or weeds directly and kill them, thereby preventing them from coming back anytime soon.

However, you have to be very careful with it, or you might end up disrupting the plants. If the damage is too much, you would have to spend years recovering your lawn.

But selecting the right option is easier said than done. The market is flooded with thousands of options, and we are here to help you sort through them.

We have compiled this guide with the top 7 products that can effectively kill Johnson grass in your lawn. You will find the pros and cons of each product listed and also an additional buyer’s guide.

So, without further ado, let’s dive right in.

Ways To Kill Johnson Grass

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So, if you’re tired of battling Johnson Grass, here’s the list of the 5 best Johnson Grass killers to help you win the war.

1. Roundup Weed & Grass Killer Concentrate Plus – Best Overall

If you are looking for an authentic formula to kill Johnson grass, Roundup Weed & Grass Killer Concentrate Plus is one of the best options to consider. It will help you easily get rid of all pesky weeds and grass that make your otherwise well-maintained garden look shabby.

Roundup Concentrate Plus Weed and Grass Killer - Includes Easy Measure...
  • Kills tough weeds and grasses to the root
  • Rainproof in 30 minutes

Why Did We Like It?

The thing that stands out about this product is the unique formula that it uses. Its potent chemical composition is effective enough to kill all stubborn weed patches.

What makes this possible is glyphosate, which is an active ingredient in this composition. Also, it has diquat dibromide that is super-efficient when it comes to removing Johnson grass.

Not only for Johnson grass, but this formula can also be easily used around your garden, driveways, or sidewalks to get rid of all kinds of unwanted weeds. We suggest that while you prepare the garden, you go ahead and mix some of this with the soil. Rest assured that it won’t harm any of your edibles.

Moreover, this item is highly concentrated. It is advisable that you read the instruction carefully and dilute it according to your requirement.

Also, this product is suitable for both large and small areas and needs only 30 minutes post-application to become rainproof.

What Could’ve Been Better?

There’s hardly any complaint that we have against this potent mix that effectively kills Johnson grass. However, the packaging of this product can be better. It is not easy to open the bottle, and once opened, the lid does not close very well. So, you might have to store it in a separate container.

  • Suitable for different areas
  • Effective formula
  • Versatile
  • Easy to apply
  • Packaging is not good
Active Ingredient(s): Glyphosate and Pelargonic acid | Volume: Varies | Type: Non-selective | Coverage Area: Up to 3000 sq. ft. | Rainproof: Yes | Pet Friendly: No

2. Compare-N-Save 016869 – Best For Affordability

Compare-N-Save is quite a popular name in the market when it comes to weed removal and their item 016869 is one that you can safely put your bets on. What’s really brilliant about this is that it does not harm any of your other plants in the garden and just effectively removes weeds.

Compare-N-Save 75324 Herbicide, 1-gallon, white
  • Rainproof in 2 hours
  • Visible results in as little as 2 to 4 days

Why Did We Like It?

Coming to the application, it can be pretty much applied anywhere. It is safe to use around your flower beds, trees, and shrubs. And if you read the instructions carefully and use the mix, then you can also use it on fruit and vegetable patches.

Moreover, this item comes as a concentrated mix. This is a huge benefit because you can adjust the dosages according to your requirements.

Usually, 3 tablespoons are enough in 1 gallon of water. However, depending on the type of weed and the size of the patches, you can change the concentration accordingly.

Furthermore, you do not have to worry in case it rains after you apply the product. This item becomes rainproof only within 2 hours of application. However, keep in mind that winter is the best time to apply this product as this is when it kills weeds in the most effective way.

What Could’ve Been Better?

It is true that the product works quite well when it comes to killing weeds. However, we will tell you that it can only work its magic when applied during the right weather conditions. So, we would suggest that you follow the user instruction carefully before you apply.

  • Can be used on multiple plant types
  • Easy to apply
  • A little is enough to kill big weed patches
  • Does not get affected by rain
  • Does not work well in bad weather
Active Ingredient(s): Glyphosate | Volume: 128 fl oz | Type: Non-selective | Coverage Area: Up to 25000 sq. ft. | Rainproof: Yes | Pet Friendly: No

3. Ortho Nutsedge Killer – Best Rainproof Grass Killer

If you are looking for an item that can kill the toughest of weeds, including Johnson grass, look no further. Ortho Nutsedge Killer is an excellent choice that can easily get this job done. This ready-to-use mixture is one of a kind and selectively kills all unwanted outgrowth in your garden without harming your plants.

Ortho Nutsedge Killer for Lawns Ready-To-Spray, 32 fl. oz.
  • Kills yellow and purple Nutsedge, Kyllinga and...
  • For Northern and Southern turf grasses

Why Did We Like It?

This product ranks high on versatility. It is a uniquely formulated herbicide that can effectively kill southern and northern turf grass along with Johnson grass. It has around 0.05% of sulfentrazone which is very effective when it comes to killing the most stubborn weeds.

Moreover, you do not have to wait for a particular season to use this herbicide. It can be used all year round on any kind of weed outgrowth on your turf or sidewalks. However, we would still suggest that you put it during the colder months because that is when it works best.

Also, rainfall is not a problem with this item. Herbicides that get washed in the rain are problematic because they do nothing to the weeds and also harm animal lives in water bodies.

With Ortho Nutsedge Killer, you do not have to worry about surface run-offs as it becomes waterproof only within 2 hours of application.

What Could’ve Been Better?

It is a ready-to-use mix that effectively kills weeds. However, do keep in mind that you need to follow application instructions to the tee. Overapplication is extremely harmful and, in the worst scenario, may even kill your plants and grass.

  • Is not susceptible to rain
  • Easy to apply
  • Suitable for multiple weed categories
  • Can be applied all year long
  • Overapplication can be harmful
Active Ingredient(s): Sulfentrazone | Volume: 32 fl oz | Type: Selective | Coverage Area: Up to 800 sq. ft. | Rainproof: Yes | Pet Friendly: Yes

4. Spectracide Weed & Grass Killer Concentrate

What if we tell you that we have a recommendation that will make your yard the envy of the town? Spectracide Weed & Grass Killer Concentrate is one such item that is easy to use and transforms your lawn into a magnificent one by killing all harmful weed outgrowth.

Spectracide Weed & Grass Killer Concentrate, Use On Driveways,...
  • KILLS WEEDS AND GRASSES: use on driveways and...
  • KILLS THE ROOT: visible results as fast as 3 hours...

Why Did We Like It?

What is really good about this product is that it does not cause any damage to your flower beds or vegetable patches. While it is true that the composition has chemicals in it, they are not harmful to your plants. It does exactly what it is designed to do – kill the weed.

Additionally, it comes with a fast-acting formula. As a result, you do not have to wait for months to see positive results. You just have to give it 3 hours to see how the weeds get killed. The moment weeds are out of the picture, your plants and grass can live healthier.

Furthermore, it is entirely rainproof. We understand how bad you feel when it starts raining right after you decide to put on the weed killer. However, with this item, you will not have to face any such worries. It gets completely rainproof within 15 minutes of application.

What Could’ve Been Better?

If you are new to the world of gardening, you might face some hardships with this product. The instructions are not very clear. We would recommend that you call a gardener or a friend who can help you with the application. And if nothing works, google it!

  • Can withstand rain
  • Shows result very fast
  • Does not damage the plants
  • Easy to apply
  • Instructions are not very clear
Active Ingredient(s): Diquat dibromide and Glyphosate | Volume: 64 fl oz | Type: Non-selective | Coverage Area: Up to 1000 sq. ft. | Rainproof: Yes | Pet Friendly: No

5. RM18 Fast-Acting Weed & Grass Killer Herbicide

We are almost reaching the end of our list, and next up, we have RM18 Fast-Acting Weed & Grass Killer Herbicide. This is best for people who do not like a long period of preparation but want to see the weeds in their garden killed fast. It is the perfect weed control solution to do away with your Johnson grass too.

RM18 Fast-Acting Weed & Grass Killer Herbicide, Spray, 1-gallon
  • Makes up to 42 gallons to ready-to-use spray...
  • Treats up to 12, 600 Square feet

Why Did We Like It?

This item is highly suitable for clearing Johnson grass and a range of other unwanted weeds that make your garden look clumsy and shabby. You can use it in the yard, garden, driveways, and even sidewalks. It does not harm your plants or vegetation, so there’s nothing to worry about on that front.

Also, it comes with a Quick Acting Weed formula that is extremely efficient in killing all harmful weeds that take the nutrition away from your plants. Within 12 hours of application, you will be able to see the difference. The weeds start to visibly die off.

Moreover, you do not have to see the weather forecast before deciding to apply this item. Even if there’s a sudden rainfall, this item will still work its magic. After application, it just needs 30 minutes to get absorbed and locked in the soil.

Additionally, the effect of this stays for as long as 6 months, and you will not have to apply it frequently.

What Could’ve Been Better?

One thing that we felt could have been better is the packaging. The cap does not close properly, and if you are not careful, you might end up spilling a lot. We recommend that you either change the cap or the container itself. It will save you from the problem of leakage.

  • Effects stay for long
  • It works very fast
  • Is not affected by rain
  • Does not harm your plants
  • Packaging is not good
Active Ingredient(s): Glyphosate and Pelargonic acid | Volume: 128 fl oz | Type: Non-selective | Coverage Area: Up to 12600 sq. ft. | Rainproof: Yes | Pet Friendly: No

Best Johnson Grass Killers Comparison Table

Product Active Ingredient(s) Volume Type Coverage Area Rainproof Pet Friendly
Roundup Weed & Grass Killer Concentrate Plus Glyphosate and Pelargonic acid Varies Non-selective Up to 3000 sq. ft. Yes No
Compare-N-Save 016869 Glyphosate 128 fl oz Non-selective Up to 25000 sq. ft. Yes No
Ortho Nutsedge Killer Sulfentrazone 32 fl oz Selective Up to 800 sq. ft. Yes Yes
Spectracide Weed & Grass Killer Concentrate Diquat dibromide and Glyphosate 64 fl oz Non-selective Up to 1000 sq. ft. Yes No
RM18 Fast-Acting Weed & Grass Killer Herbicide Glyphosate and Pelargonic acid 128 fl oz Non-selective Up to 12600 sq. ft. Yes No
A beautiful green landscape with a lot of trees under a cloudy sky

Buying Guide For The Best Johnson Grass Killer

We hope that you have gone through the above list thoroughly, and that must have given you some clarity on how to choose a good Johnson grass killer.

However, we understand that this information is not sufficient, and you might need a little more help to clear up all your confusion.

While it is essential that you know about the composition and features of the above-mentioned products, there are more things to take care of. Besides these, there are a few significant considerations to keep in mind while selecting the best weed-control herbicide for your lawn.

In this section, we will be discussing these factors. So, without more delay, let’s see what they are.

  1. Rainproof

You must have come across rainproofing quite a few times in this guide already. It basically denotes how long it would generally take for your weed controller to become resistant to rain.

You must already know that rain and water are good at diluting chemicals and making them become less effective. The same can happen to a weed killer too. If it starts raining right after you apply the product and gets diluted, you might have to re-apply very soon.

Depending on your location, choose an option that will suit your purpose. If you stay in an area that gets a lot of rainfall, go for an option that comes with a short rainproofing period.

In case your product does not have fast rainproofing features, do not apply it on days when there is a forecast of rain.

  1. Organic/Inorganic

This debate has survived for a long, and we have to say that this one completely boils down to personal preferences.

It is true that organic weed killers are a lot safer as compared to their inorganic counterparts and can be easily used around kids and pets. They are also highly environment-friendly and do not cause any unwanted harm.

However, it must also be kept in mind that they are a little expensive. So, if you are on a budget, they might not be very affordable.

Inorganic (chemical) weed controllers, on the other hand, are composed in a lab and are comparatively much more powerful than organic ones. They require a lesser number of applications too. However, they can be pretty harmful, and you have to be careful not to touch or breathe the chemical in when using them.

  1. Area Covered

Most of the options that you will come across have to be combined with water before application. In case you choose a more concentrated option, make sure that you read the instruction very carefully and dilute it in proper proportions before applying it.

Depending on the concentration and size of your weed patches, decide on the quantity that you would be applying.

Frequently Asked Questions

Are Johnson Grass killers safe for pets and the environment?

Most Johnson Grass killers are safe for pets and the environment when used according to the manufacturer’s instructions. However, it is important to keep pets and children away from the treated area until it dries or settles into the soil.

How long does it take for Johnson Grass Killers to work?

The time it takes for Johnson Grass killers to work varies depending on the product and the severity of the infestation. Some products may show results in a few hours, while others may take several days or weeks.

Can Johnson Grass come back after using a weed killer?

Johnson Grass can come back after using a weed killer if the roots were not completely destroyed. It is important to follow up with regular maintenance and reapplication of the herbicide if necessary.

Can Johnson Grass Killers be used on other weeds?

Most Johnson Grass killers are non-selective, meaning they can also kill other weeds and plants. It is important to read the label and only use the product on the intended target.

What is the best time of year to use Johnson Grass killers?

The best time of year to use Johnson Grass killers is during the growing season when the plants are actively growing. This can vary depending on your location and climate. It is best to read the label and follow the manufacturer’s instructions.

Asian man watering his garden. , farmer kills weed spraying pesticides in field by manual backpack sprayer. , gardener kill the weed.


Finally, we have reached the end of this guide in which we discussed the best products to help kill Johnson grass. And we only hope that you have been able to benefit from the information that we have shared.

We had a great time using and reviewing these products, and we hope that you have enjoyed reading about them too!

But before we bid adieu, we would like to share our favorites with you. Roundup Weed & Grass Killer Concentrate Plus takes the award for being our all-time favorite. If you are looking for an option that is affordable and easy to apply, Compare-N-Save 016869 is a good bet.

And if you are looking for an item with faster rainproofing features because your area gets a lot of yearly rain, Ortho Nutsedge Killer is a perfect choice.

And with that, it’s a wrap. Until next time, happy gardening!

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