How to Get Rid of Japanese Knotweed

Want to know how to remove Japanese knotweed? In this guide, we discuss the steps required to achieve this, as well as other relevant subjects like the tools, safety equipment, and materials needed. We will discuss three different methods that can be used to remove Japanese knotweed.

What Is Japanese Knotweed?

Japanese knotweed is a non-native herbaceous perennial plant. Since the UK is not a natural ecosystem for knotweed, there aren't any natural enemies to help stop it excessively spreading and having a negative impact on local ecosystems.

It is often most prevalent on hedgerows, waste grounds, riverbanks, wetlands, and roadsides. However, it can also be found on properties across the UK and often causes problems for other plants in the garden.

Therefore, it's important to have Japanese knotweed removed carefully to prevent harmful and excessive growth. Not only that, but under the Wildlife and Countryside Act 1981 in Great Britain, it's an offence to plant Japanese knotweed or otherwise cause it to grow in the wild. Allowing the plant to spread onto neighbouring land can also lead to legal action, although having it on your land isn't an offence in itself.

For best results, hiring a professional who specialises in Japanese knotweed removal will ensure the job is carried out correctly.

What Tools Do I Need to Remove Japanese Knotweed?

As there are several approaches to getting rid of Japanese knotweed covered in this guide, below is a list of the tools required for each one:

Digging Up Knotweed:

• Garden spade or shovel

Cut Stem Application Approach:

• Spray bottle
• Secateurs or pruning shears

Foliar Spray:

• Handheld garden sprayer
• Knapsack sprayer (optional)

What Safety Equipment Do I Need for Japanese Knotweed Removal?

Below is a list of the main safety equipment required, although when foliar spraying, always follow manufacturer's guidelines before applying:

• Rubber safety gloves
• Protective eyewear
• Protective shoes
• Long sleeves or protective clothing

What Materials Do I Need to Get Rid of Japanese Knotweed?

Digging Up Knotweed:

• Garden waste bags

Cut Stem:

• Glyphosate-based herbicides
• Water
• Garden waste bags

Foliar Spray:

• Glyphosate herbicide
• Garden waste bags

Find Tradespeople, compare up to 3 quotes!

It's FREE and there are no obligations

Get started

Preparing to Remove Japanese Knotweed

Next, preparations are needed before the removal can take place. If you are unsure about anything involved in the process, you should hire a professional.

Japanese Knotweed Identification

There are plenty of ways to spot Japanese knotweed and differentiate it from other plants. Let's look at some main pointers.

How to identify Japanese knotweed:

• The stems feature green and red/purple flecks with a zigzag pattern of growth.
• The leaves are lush green featuring a pointed tip and a shovel-like shape.
• It can grow up to 3-4 metres in height, with certain varieties reaching even higher.
• During late summer, flowers have creamy white coloured panicles.

There are more identifiable tips worth contemplating. However, if you are unsure whether plants on your property are Japanese knotweed, you should hire a professional.

Examining the Grass

Next, you'll want to examine the area to assess what is the best method to use to deal with the Japanese knotweed.

How to Get Rid of Japanese Knotweed Yourself

Below we review different methods of removing Japanese knotweed. It's important that once you are finished you wash your hands thoroughly and if you are using glyphosate-based products, let the herbicide treatment dry before allowing people or pets access to your garden.

Also, be aware that if the herbicide treatment is accidentally sprayed on other plants, they may not survive.

Never mow, strim, or flail knotweed because it spreads the plant further and could be an offence.

Method 1 — Dig Up Japanese Knotweed

Step 1 — Moisten the Soil

It is important that the soil is moist before digging up the Japanese knotweed. This may be the case due to sufficient rainfall. However, if not, you should dampen the area using a garden hose.

Step 2 — Remove the Plant

Once the soil is moist, employ a garden shovel or spade to upend each full plant. This would include removing the runners and the root system in their entirety, which is very difficult as the roots can easily reach 1m deep or more.

It's important that the entire plant is removed, as even a small 1cm piece of the root can resprout and establish a new colony.

Try to avoid chopping the roots up, and sift the soil to get rid of any fragments. Check throughout spring and summer for any regrowth that needs to be dug out.

Step 3 — Dispose of the Plant

The removed plant should be carefully placed into a garden waste bag, ensuring nothing has been left behind.

Japanese knotweed should not go in a household general waste or green waste bin, or a home compost heap. You can use a waste removal company or contractor, but they must be a registered waste carrier and take it to a landfill or incineration site with a permit to accept knotweed.

You can also burn the plant if your local council allows it, but keep in mind that parts of the plant can survive burning.

Burying it where it grew is another option. You'll have to bury it 5 metres deep, 2 metres if it's sealed in a special membrane, and inform the Environment Agency (in England, rules in other parts of the UK may vary) at least a month before the work.

Review the area you've cleared about twice every month to check for any evidence of the weed returning.

Method 2 — Cut Stem Application

Step 1 — Prepare the Herbicide

This method involves using a spray bottle with a glyphosate-based herbicide. Please make sure to follow the instructions given by the manufacturer and to follow COSHH guidelines (Control of Substances Hazardous to Health). Sometimes, the manufacturer will suggest using the product undiluted, but in other cases, it will be advised to mix it with water for a 1:1 ratio.

Step 2 — Cutting the Stems

You'll want to cut the stems of the knotweed at a position that is 2 to 3 inches above the level of the ground. As soon as this is done, spray onto the stem that has been cut. Give it a week or more before moving the treated stems or simply cutting them.

This will give the chemical application time to work. Cut, spray or pull up by hand any remaining sprouts that pop up. It is best to treat weeds in late summer or early autumn, usually during a dry spell as recommended on the product's label. For this method, you should wear the safety equipment described earlier.

Method 3 — Foliar Spray

Step 1 — Spray Application

Another method that is similar to the prior involves applying a foliar spray with a handheld garden sprayer.

This approach is best suited to situations where there is a large colony of Japanese knotweed. If the instructions say to, dilute the weedkiller following the recommended amount of water.

Wet the knotweed down using the handheld garden sprayer. Avoid spraying the leaves to the point that you get runoff. Repeat this once a year for 3 years, or longer if the plant persists after this time.

It is best to apply a foliar spray in late autumn, during dry conditions. You should wear the safety equipment described in this article for this method.

Other Types of Invasive Knotweed

In this section, we'll discuss the other types of invasive knotweed that you might find in your garden.

Giant Knotweed

This type of knotweed tends to grow larger than most, and stems can reach up to 4-5 metres in growth during just one season. You may spot a heart-shaped base on each of these and alternate leaves can grow to as much as 30cm in length.

The stems tend to be knotted, woody, and similar to bamboo. A cut stem application or foliar spray is the best course of action when dealing with this type of knotweed. Giant knotweed can be particularly troublesome and significantly impact the aesthetics and biodiversity of your property.

Bohemian (Hybrid) Knotweed

This type of knotweed is a hybrid of Japanese and giant knotweeds. It can be very difficult to remove as it combines the rapid growth of Japanese knotweed with the larger size of giant knotweed.

You can identify it by its heart-shaped leaves, upright, thick, bamboo-like stems, and small, creamy-greenish-white flowers that bloom in late summer.

Dwarf Knotweed

While not as tall as other varieties, left unattended it can grow to around a metre. The leaves of dwarf knotweed feature a leathery texture and edges that are crinkled.

You'll often find pale pink or white dwarf knotweed flowers appearing towards the end of the summer. As they mature, these flowers can redden or become dark pink.

Ask a Trade

Got a question that only a tradesperson can answer? We have thousands of trades ready to answer any question you may have.

Ask your question

FAQs