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



Our Top PickOur Top PickHstcstbl-table__image Roundup Weed & Grass Killer Concentrate Plus
  • Rainproof in 30 minutes
  • To be used in a tank sprayer
  • Weighs 1.28 pounds
Hstcstbl-table__image Compare-N-Save 016869
  • Rainproof in 2 hours
  • 41% glyphosate
  • Covers over 25,000 square feet
Hstcstbl-table__image Ortho Nutsedge Killer
  • Weighs 2.4 pounds
  • Can be directly used
  • Kills over 50 types of tough weeds
Hstcstbl-table__image Spectracide Weed & Grass Killer Concentrate
  • Fast-acting formula
  • Comes in concentrated form
  • Rainproof in 15 minutes
Hstcstbl-table__image Doctor Kirchner Natural Weed & Grass Killer
  • Made of natural ingredients
  • No mixing required
  • Kills weed in 12-24 hours
Hstcstbl-table__image RM18 Fast-Acting Weed & Grass Killer Herbicide
  • Ready-to-use mix
  • Can be used on 12,600 square feet
  • Shows results in 12 hours
Hstcstbl-table__image Knock Out 342054.0 Weed and Grass Killer
  • Concentrated weed killer
  • Weighs 1 pound
  • Kills johnson grass, dandelion, and many more types of weed

Olympus digital camera

  1. Roundup Weed & Grass Killer Concentrate Plus

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
  1. Compare-N-Save 016869

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 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
  1. Ortho Nutsedge 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 outgrowths 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 that 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 in your turf or sidewalks. However, we would still suggest that you put it during the colder months because that is when it works the 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
  1. 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
  1. Doctor Kirchner Natural Weed & Grass Killer

We know that many people do not like to spray harsh concentrated chemicals around their yard to kill the weed. If you are one of them, then Doctor Kirchner Natural Weed & Grass Killer is a good bet for you. This natural weed killer is one of a kind, and it does not cause harm to your plants or the environment.

Doctor Kirchner Natural Weed & Grass Killer (2.5 Gallon) No Hormone...
  • A natural weed killer Made from ocean salt water,...
  • Our non selective ready to spray Natural Weed &...

Why Did We Like It?

The best thing about this item is that you do not have to keep it away from your kids or pets. After you apply it, they can still play in the garden without any fear. This is completely safe for kids, pets, and the environment in general.

 Its main aim is to kill the weeds in your yard, and it does that with sheer brilliance!

Additionally, it is extremely easy to apply this product in your garden. You won’t be required to spend any time mixing the item. You can directly use it from the container that it comes in. All you have to do is to attach a sprayer head, and you are good to go!

Moreover, you can see the results of the application quite fast. It does not take weeks or months to show results. After applying, wait for 12-24 hours to see the weeds slowly dying away.

Also, this product can be stored for a very long time, without it going bad.


What Could’ve Been Better?

Despite it being a brilliant performer, we have to say that it is quite a pocket pinch. Also, it does not come with a sprayer head. You have to take a trip to the nearest hardware store to get your hands on one.

  • Environment-friendly
  • Very easy to apply
  • Acts very fast
  • Long shelf life
  • Does not have a sprayer head in the package
  1. 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, 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.

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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
  1. Knock Out 342054.0 Weed and Grass Killer

We have reached the end of our list, and there is no way we could have wrapped up without having mentioned Knock Out 342054.0 Weed and Grass Killer. It is a very effective herbicide as it attacks the weed at the roots. Thereby, it completely destroys the chances of johnson grass or any similar growth ever to return.

Knock Out 342054.0 Weed and Grass Killer, 32 oz
  • Knock Out Weed & Grass Killer 32oz Kills the root
  • For use around flower beds, trees and shrubs

Why Did We Like It?

We understand that it gets annoying to buy different sets of herbicides to tackle different types of weed outgrowth. However, with this item, you will have to face no such problem. It is quite versatile and can be used on a variety of unwanted weed outgrowths in your garden.

Additionally, the weather is not a major determinant when it comes to using this product. You do not have to bear in mind how the day is going to be before deciding to apply this item. It becomes rainproof in less than 2 hours of application. So, if there’s a forecast of rain, just make sure that you apply it 2 hours before it starts pouring.

Moreover, this can be used as a potting mix as well. In case you decide to put it in preparing your flower beds, do wait for 1-3 days before planting the trees and shrubs. If you are going to put lawn grasses, consider planting them 7 days post-application.


What Could’ve Been Better?

Despite its excellent performance, it has to be mentioned that the packaging of the product is not really great. The cap of the bottle is pretty loose and does not stick well. In case you are storing it in your cabinet, be careful to make sure it does not leak.

  • Can be used on different types of weed
  • Suitable for all weather conditions
  • Can be used as a potting mix
  • Easy to apply
  • Leaky container

A beautiful green landscape with a lot of trees under a cloudy sky

Johnson Grass Killer Buyer’s Guide

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 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 make them become less effective. The same can happen for 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 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 the 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.

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 the perfect choice.

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

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Aida Vasquez
Aida has been part of Architecture Lab ever since 2011 when she started ghost writing for the website on art and design topics, today she is our veteran design contributor, covering a wide array of topics that fuel her creativity.
Aida Vasquez
Aida Vasquez
Aida has been part of Architecture Lab ever since 2011 when she started ghost writing for the website on art and design topics, today she is our veteran design contributor, covering a wide array of topics that fuel her creativity. Highlights Aida is the first design contributor of Architecture Lab since 2011 She surges writing inspiration from real life as an avid architecture-art seeker always on the move She reviews and writes about products that she deems "cool enough" Experience Aida has been writing for Architecture Lab for almost 12 years now, writing about anything and everything in the art and design niche, every piece she writes she aces with extraordinary attention to detail and a mountain of research to back it up. When asked what drives her curiosity in realm of design Aida replied that: " Every object is the thought process of its creator at a given point in time, often the result of a years struggle that we get to enjoy so casually, we should never overlook the effort our fellow peers, even if it comes in absolutely stupidly mediocre design." Education Aida is a graduate of ESAD – Escola Superior de Artes e Design in Porto
TITLE | Design Contribuitor at Architecture Lab
About Architecture Lab Architecture Lab is a MKR.S Media brand, a website devoted to extraordinary design and aesthetics aiming to promote exceptional aesthetic values and sustainable design in all it’s shapes and sizes. Learn more about us and our editorial process and feel free to contact us if you would like to see something in particular on the website, our certified experts will get back to you with the most trustworthy advice as soon as possible. Read all articles by Aida

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