Best Herbicide for Japanese Knotweed: DIY!

Japanese knotweed is a fast-growing, invasive plant species that can quickly spread and overrun natural habitats. It’s no wonder it’s one of the most hated plants in the world! To make matters worse, Japanese knotweed is incredibly difficult to eliminate. In this blog post, we’ll explore the best herbicide for Japanese knotweed and provide some tips for using it safely and effectively.

What is Japanese Knotweed?

Japanese knotweed (Fallopia japonica) is a fast-growing, vigorously spreading plant that is native to Japan. In the late 1800s, it was introduced to North America as an ornamental plant and has since become naturalized there.

Japanese knotweed is now considered one of the most invasive plants in the world.

This perennial plant can grow up to 10 feet tall, with hollow stems that are reddish-purple in color. The leaves are heart-shaped and about 4 inches wide, with serrated edges. The small white flowers bloom in September and October, followed by black fruits.

Japanese knotweed spreads rapidly via its underground root system, extending up to 20 feet from the main plant. The roots can grow up to 3 feet deep, making this plant difficult to control or remove once it has become established.

Japanese knotweed can outcompete native plants for resources and quickly form dense stands that crowd out other vegetation.

This species is particularly problematic because it can tolerate various environmental conditions, including shade, drought, and flooding. It also has few natural predators or diseases in North America.

Japanese knotweed is extremely difficult to control once it has become established and often requires multiple years of treatment with herbicides to achieve any level of control.

Why is It a Problem?

Japanese knotweed is an invasive species that can cause problems for homeowners, businesses, and municipalities. The plant can grow quickly and aggressively, crowding out native plants and causing damage to infrastructure.

Japanese knotweed can also be difficult to control once it has established itself in an area.

Knotweed is difficult to control because it can regrow from even a small piece of stem or root. Mowing or pulling the plant will not kill it, and herbicides that work on other plants are ineffective on knotweed. As a result, controlling this plant can be costly and time-consuming.

The Best Herbicide for Japanese Knotweed

Japanese knotweed is an invasive species that can cause serious damage to your property. If you have this plant on your property, removing it as soon as possible is important.

The best herbicide for Japanese knotweed is glyphosate. Glyphosate is a herbicide that kills plants by interfering with their ability to produce proteins. It’s the active ingredient in Roundup and is very effective at killing Japanese knotweed.

herbicide for japanese knotweed
Bob Vila

How to Use the Herbicide

To use the herbicide, mix it with water in a pump sprayer according to the directions on the label. Be sure to wear protective clothing, including gloves, long sleeves, and pants, when handling the herbicide.

Apply the herbicide to the leaves of the Japanese knotweed plants, taking care to avoid contacting any other plants or surfaces.

The herbicide will kill the plants within a few days. Repeat applications may be necessary to completely eradicate Japanese knotweed.


Japanese knotweed can be a difficult invasive weed to get rid of. However, with the right herbicide and application techniques, you can effectively eradicate it from your property.

With careful consideration, proper application, and persistence, we believe this pest will soon disappear from your garden or lawn! Thank you for reading this blog article, and feel free and welcome to continue doing it in the future!

Also read: The Secret To Japanese Garden Design

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