If you ask ”how fast does Japanese knotweed grow?” you might have heard about the invasive nature of this plant or even suspected it could be growing on your property. In this article, we answered the most asked question about Japanese knotweed.

We also tell you why you need to get rid of it and how to do it so fast.

Growth of Japanese knotweed growing fast on a neighbour’s property – over 3 metres in height

How does the Japanese knotweed spread?

This weed produces rare seeds.  It is also worth noting that the Japanese knotweed species in the UK are female and hermaphrodite. The female species cannot reproduce on their own without the male species. This is why the knotweed seeds dispersed in the UK are termed sterile.

The knotweed in the UK spreads through the dispersion of the stem cuttings, roots, and crowns.  The relocation of soil from the contaminated area to clean soil is the most common way this weed is spread.

Regardless of the size of the stem cuttings, roots, or crown, the Japanese knotweed will grow in no time.

New shoots can grow through any type of soil and at a pace too
New shoots can grow through any type of soil and at a pace too

How quickly does the Japanese knotweed grow?

The Japanese knotweed is the fastest-growing weed in the UK. Several studies have been done about the weed’s growth, and the majority seem to conclude that the plant grows up to 10 cm tall in a day during summer.

That is how tall the weed grows each day of summer, and you can see it growing everywhere, including on cement pavements and wall joints!

The knotweed grows in different climatic conditions around the world. It is one of the most invasive weeds there is. Specialists have found out that its distribution was a result of improper disposal. The plant also spread due to the spread of contaminated soils. 

The knotweed grows even from tiny cuttings because UK soil is moist throughout the year, making it grow fast and easily.

The stems of Japanese Knotweed can grow up to 10cm a day
The stems of Japanese Knotweed can grow up to 10cm a day

How deep are the Japanese knotweed roots?

The weed’s rhizome system stores the requirements for plant growth. The roots run deep and wide. The roots grow so fast and measure between 2- 3 meters deep and 7 meters horizontally.  This only means that you will have to put in a lot of work before you dig them up the soil.

How to stop Japanese Knotweed from growing?

 The weed causes massive damage if left untreated. It blocks direct sunlight from reaching plants causing weathering and finally death.

The knotweed leads to soil erosion when growing on the river banks. Its invasive nature causes the weakening of soil particles. The plant exploits tiny openings in the pipes and cracks of houses. The root system grows wide, leading to immense damage to structures.

For example, in the UK, this weed has led to a decrease in the value of several properties.

In Japan, where the knotweed originated, the weed is controlled by predators. Unfortunately, such predators are not found in the UK; other methods of elimination have to be used.

Specialists do not recommend that you try and remove the plant yourself. The UK government is clear about the removal and disposal of this plant. The guidelines are pretty strict; hence you may end up facing the law if you break any of the laid rules.

To be on the safer side, we advise that you seek professional help. Remember that this plant is invasive, making it challenging to eliminate it without proper equipment and skills.

So, what kills the Japanese knotweed permanently?  There are not many solutions out in the market that can kill this weed permanently.   Glyphosate-based herbicides are the only compounds that can completely get rid of this weed.

One downside of these chemicals is that they will kill any plant that is near the weed. This remedy is suitable for those with large areas covered with Japanese knotweed without any plant that should be spared.

Glyphosate kills the leaves, roots, and stems, unlike the popular contact herbicides that only kill leaves and stems. The ideal time to spray the plant is late summer or early autumn.  During this period, the plant flowers mean that the foliage facilitates more nutrients to the rhizomes for storage.

With so many leaves acquiring nutrients, sun and water, it is no wonder Japanese Knotweed goes so fast
With so many leaves acquiring nutrients, sun and water, it is no wonder Japanese Knotweed goes so fast

Can you burn the Japanese knotweed?

Other than using herbicides, you may choose to burn the weeds. This step comes after the knotweed removal. The disadvantage of this method is the roots may not smoke, hence regrowth after a few weeks.

We recommend that you get in touch with a certified expert after you burn the knotweed. An expert company will properly inspect your property and make recommendations.

Another option for getting rid of the knotweed is to prevent the spread of neighbouring properties. Remember, your neighbours might sue you for damages as long as they can prove that the weed originated from your land. The impenetrable barrier is buried 3 meters into the ground.

This stops the plants from growing in other areas. This weed cannot grow through the barrier making the spread contained.  You will need a special wire and fence to do all this.

Finally, we recommend that you skip all the actions above and contact a knotweed removal specialist. This will save you time and headache and ensure proper steps are taken as early as possible to stop the spread. It is quite challenging to carry out the removal process.

There are several certified companies that you can contact. An ideal company should ensure proper identification, removal, and treatment. Remember, there are several plants mistaken for Japanese knotweed, you want to be careful not to leave any stone untied.

How fast does Japanese knotweed grow in your garden is worry for all property owners
How fast does Japanese knotweed grow in your garden is a worry for all property owners

Want to know more about how fast Japanese knotweed grows?

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

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