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Best Herbicides For Japanese Knotweed (Ultimate Buying Guide)

Japanese knotweed is, in fact, a plant that comes from the family Polygonaceae. It is a plant that is native to Japan, China, and Korea. However, it doesn’t mean that this plant cannot be seen in other places as well. It is known as a perennial plant that comes and goes once a year, during warmer seasons like spring and summer.

Anyways, there are many people that want to get rid of this plant, and they have their own opinions and ideas. Well, if you are one of those people, I would gladly say that getting rid of Japanese knotweed is the reason why I am writing this article.

Based on research, you may have encountered different ways of killing Japanese knotweeds, such as cutting them off and mowing them, but still, the most effective way of doing so is the use of different substances, mostly herbicides!

The last word in the previously written sentence is our aim in this article. Here, you will find the best herbicides for Japanese knotweed that will help you get rid of the plant in the easiest way possible.

Now, I know that I mentioned a lot of things, but let us get this article started and let me help you find the best herbicide for Japanese knotweed!

The Top 5 Best Herbicides for Japanese Knotweed

5. Killzall – Best Budget

You may already know that I love to add the first item when it is a budget one, and I am doing it here as well. The Killzall herbicide is one of the cheapest, especially compared to the other herbicides that I will mention in this article.

Hence its name, the Killzall will definitely kill whatever you may need to, from the unwanted different types of weed that may appear in your garden to the biggest growing plants like Japanese knotweed.

The Killzall herbicide implies within 41% of glyphosate, and it will kill the Japanese knotweed plant in 2 hours, which is a quite quick time. It covers up to 3200 square feet in case you want to kill grass or weed of any kind, and it does it down to the roots part.

In order to replant, it all varies on the type of plant that you want to plant, but still, it is said that two weeks is more than enough for replanting.

Why Should You Buy It?
Being the best budget herbicide, you may want to choose it in case you don’t want to spend a lot of money!

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4. Green Gobbler – Best Mid-Range

Another herbicide listed by the price tag that it comes at is the Green Gobbler. Here it is found as one of the herbicides that have what may be called a “normal price tag”. Well, I couldn’t leave it unmentioned here!

You know what? This herbicide can also be listed as an all-natural one because it is only made of organic substances, and in fact, it doesn’t own any percentage of glyphosate. Even though it may sound weird, the Green Globber will definitely kill your Japanese knotweed plant, so you don’t have to worry.

As I said organic, the Green Gobbler owns 20% of vinegar and it is made of corn mostly. Still, it will kill the plant better and faster than you can ever imagine. By the way, the Green Gobbler doesn’t own cancer-causing chemicals in any way.

When it comes to replanting, being organic, you can easily plant any type of plant on the same soil by waiting just two days.

Why Should You Buy It?
A normal price tag and normal herbicide, well this is the mid-range herbicide that you can choose, in order to have quantity and quality combined.

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3. Ranger+ – Best High-End

Now, the Ranger+ is another herbicide that definitely deserves a place in my article! Based again on the way I listed it, it is a herbicide that has a higher price tag, and if you have an idea about herbicides and killers, you may know that they are quite affordable. Well, Ranger+ has changed the game, it is still affordable, but a little bit pricier than the ones we are used to seeing.

Just like the first mentioned herbicide, the Ranger+ will kill not only your Japanese knotweed, but it will also do an amazing job of killing unwanted grass and unwanted pests as well.

Again, compared to the other two mentioned, the glyphosate that is added to this herbicide is at 41%. The best way of using this herbicide is to combine it with water, and directly pour it on the roots of the plant that you want to kill, in this case, the Japanese knotweed.

What should be mentioned about this herbicide is that it doesn’t affect the replanting and the growth of new plants, as it is completely concentrated on killing big roots. That concludes with the fact of replanting new plants in the same soil. There won’t be any kind of problem.

Why Should You Buy It?
Now, differing from the ones mentioned above, this herbicide is for those people that don’t care about the money, as long as the job is done!

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2. Compare-N-Save – Best Runner-Up

Moving along, here appears a quite famous herbicide, the Compare-N-Save. It is one of the herbicides that are used by many people, gardeners mostly, in order to kill different plants as well as other unwanted types of weeds.

The Compare-N-Save herbicide is a very powerful one, and it will help you get rid of different unwanted plants or weeds, besides the Japanese knotweed. You will be more than free to use it wherever you want. It is important to mention that if you want to use it as a spray, just one gallon of this herbicide will make up to 85 gallons.

Anyways, this herbicide has glyphosate at 41% as well, and it is powerful enough to cover up to 25000 square feet. Another important thing is that this herbicide is rainproof, so it can be used in different weather conditions.

After applying this herbicide, you will find the results at two to four days, but the replanting is more than safe to be done. You can plant any other plant without any kind of problem.

Why Should You Buy It?
If you have a big garden and super-big Japanese knotweed, let me say that the Compare-N-Save will do the job perfectly by completely killing it!

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1. Roundup Ready-To-Use – Best Overall

Last but not least, here goes the amazing Roundup Ready-Tp-Use. Hence its name, it is indeed ready to be used wherever and whenever you want. It will do an amazing job killing Japanese knotweed among other different unwanted plants or weeds.

There is no other word to describe the herbicide Roundup besides mentioning the fact that is indeed an amazing one in killing Japanese knotweed. It is one of the most used herbicides by many people all around the world.

Even though there is no specification on the amount of glyphosate based on percentage, the Roundup herbicide definitely owns it, as it helps not only kill Japanese knotweed but any type of thing that you want to get rid of.

It is super powerful and goes deep down on the strongest roots that any plant may own, and it will kill them. In order to replant, you may want to wait for a week, as being this powerful you wouldn’t want to cause damage to other plants.

Why Should You Buy It?
Listed as the best overall, the Roundup herbicide is not only good to kill Japanese knotweed, but in fact, it is the perfect one and the best choice!

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Frequently Asked Questions

Why would one kill Japanese knotweed?

The answer to this question requires a specific article, but still, I would like to mention some of the most important things here, because they are a few in number.

Japanese knotweeds are plants that grow super fast. During summer they can achieve growth of 10cm in just a day, and I am pretty sure that it will fully destroy the looks of your garden. In a general form, Japanese knotweed can be grown up to 4m, which is indeed huge. The plant has very strong roots that can destroy different things. By the way, based on research, many homeowners and Japanese knotweed owners were sued because of this plant, as it can move onto other people’s properties as well.

I am well aware that there are many other things that you may want to know, but for now, the reasons why you should kill Japanese knotweed are those mentioned above.

What is the main substance that kills Japanese knotweed?

Based on the herbicides mentioned above and based on my knowledge and a little bit of research, the main substance, a chemical one, that kills Japanese knotweeds is glyphosate. As you can notice, all the items and products that I mentioned in this article have glyphosate within, as the main substance.

Can I use bleach or diesel to kill Japanese knotweed?

You may have heard that bleach and diesel are very powerful substances or chemicals that destroy many things that you may have around, and in fact, they really are. However, when it comes to killing Japanese knotweed they are nothing compared to this strong plant. It may destroy a little bit the knotweed’s leaves, but leaves only. The strong roots of Japanese knotweed will remain the same.

What if I burn the unwanted Japanese knotweed?

Japanese knotweed is a quite tricky plant, and the burning process makes it even trickier. That’s because if you burn this plant, the top parts of it will be dead, but again, if you go check out its roots, you will notice that they are really untouched, as they are very but very strong. I wouldn’t recommend killing Japanese knotweed while burning it, because there is no effect.

Final Words

Here we are at the end of this article! I am more than glad to mention again that the herbicides that are mentioned in this article are indeed the ones that will kill the Japanese knotweed in the best way possible!

Anyways, I hope that this article will help you find the best herbicide for Japanese knotweed!

Further Reading

Before going, let me mention for you some other things as well, that include other articles that I have already written!

There are many things that different plants deal with, but still, there is one specification and it is the coloration of leaves.

In case you are dealing with yellow leaves on some plants, but you don’t know the reason why they happen, you can check out why kalanchoe leaves turn yellow, the reasons why iris leaves turn yellow, and also green bean leaves turn yellow.

Also, I would like to add also why the browning coloration happens in fiddle leaf fig leaves.


Natalia Michalska

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