Japanese knotweed is a fast-growing, invasive weed that can cause serious damage to your property. 

So, what height can Japanese knotweed grow to and why does it pose such a danger?

Japanese knotweed can typically grow up to 3 meters in height and spread rapidly, making it difficult to control. Left untreated, it can damage foundations, walls, and even sewer systems.

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How tall can it grow?

Japanese knotweed can grow to be quite tall, sometimes reaching heights of over 10 feet.

Japanese knotweed can grow quite quickly, sometimes putting on as much as 3 feet of new growth in just a few weeks.

This rapid growth rate, combined with its aggressive root system, makes Japanese knotweed a very difficult plant to control once it has become established.

In fact, the plant is considered to be one of the most invasive species in the world, and it is capable of causing serious damage to buildings and infrastructure.

As a result, it is important to be aware of the potential for Japanese knotweed to grow to tall heights in order to avoid its negative impacts such as blocking the light out to your other plants in the garden and the precious nutrients it consumes in the soil below.

At two weeks the Japanese knotweed shoots are already several inches high
At two weeks the Japanese knotweed shoots are already several inches high

Japanese knotweed grows so fast it can add between 10 to 20mm of growth per day across multiple shoots on the main clump above the ground.

Within a month it can be over several feet high and as the leaves roll out and absorb as much light and water as possible it speeds up its growth, adding between 20 to 30mm of growth a day.

After a few days growth the Japanese knotweed shoots are already at 160mm
After a few days growth the Japanese knotweed shoots are already at 160mm
Japanese knotweed shoots 2 days later
Japanese knotweed shoots 2 days later

What are some of its features?

The plant is characterized by its hollow stems and heart-shaped leaves, which are arranged in a zig-zag pattern along the stem. The plant produces small white flowers that bloom in August or September.

Japanese knotweed is a serious problem because it outcompetes native plants, reduces biodiversity, and can cause damage to infrastructures such as buildings and roads.

Japanese knotweed can grow in a variety of habitats, including forests, fields, and along roadsides. The plant spreads rapidly, crowding out native vegetation. 

It is very difficult to control once it becomes established, so it is important to take steps to prevent its spread.

Japanese knotweed at 7 days growth
Japanese knotweed at 7 days growth
Japanese knotweed at 10 days growth
Japanese knotweed at 10 days growth
Japanese knotweed at 14 days growth
Japanese knotweed at 14 days growth
Japanese knotweed at 18 days growth
Japanese knotweed at 18 days growth

The tallest recorded case of Japanese knotweed

Japanese knotweed is a fast-growing plant that can reach up to 12 feet in height. Typically it grows to between 3 and 3.5 metres and covers an area densely. This is why Japanese knotweed is easily mistaken for bamboo.

As for the tallest recorded case of Japanese knotweed being found, nothing has been recorded beyond 3.5 metres which seems to be the genetic maximum height of this plant.

Within weeks the Japanese knotweed shoot has leaves blossoming and absorbing sunlight
Within weeks the Japanese knotweed shoot has leaves blossoming and absorbing sunlight

The best course of action to get rid of it

Japanese knotweed is an invasive plant that can cause serious damage to your property. If you already have Japanese knotweed on your property, there are some steps you can take to prevent it from spreading.

First, cut the plant back to the ground level and remove all the leaves. Then, treat the area with a herbicide that contains glyphosate. You will need to reapply the herbicide several times throughout the growing season to kill the root system.

Once the plant is dead, you can prevent regrowth by covering the area with a black tarp or plastic sheeting. Japanese knotweed is difficult to control, but by following these steps you can prevent it from causing further damage to your property.

In conclusion

How Tall Can Japanese Knotweed Grow To?

If you have Japanese knotweed on your property, it is important to take action quickly. Our team of experts are experienced in controlling this weed and can help you get rid of it safely and effectively.

So, if you want to control this weed before it takes over your garden and kills your other plants, as well as risk the structural integrity of your property, then you need to act fast.

Want to know more about Japanese knotweed?

Knotweed Removal aims to provide the most up-to-date information, help, and advice for YOU to make informed decisions. If you are unsure or uncertain about how to proceed, please reach out to us and we will gladly come back and advise you as best we can.

Governmental advice can be found here and the UK law covering the removal of Japanese Knotweed as stated under the Wildlife and Countryside Act 1981 can be found here.

The best means to contact us is via our email – hello@knotweedremoval.tips

Do not forget we have a library of blogs covering many areas relevant to Japanese Knotweed, our free downloadable How-to Guides, and Product Reviews on the latest methods being employed to eradicate or remove Japanese Knotweed.

Knotweed Removal, UK

Andy Woolley is an accomplished expert in the field of invasive weed management, with a specific emphasis on Japanese knotweed. He has extensive experience researching and managing invasive species and has authored numerous articles on the subject. His deep knowledge of invasive weed control has made him a respected authority in the industry.

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