Winter and autumn come with some relief for people trying to eradicate the Japanese knotweed on their property. Most property owners assume that Japanese knotweed dies in winter only to grow back when the season is over.

So, yes, Japanese knotweed will die back in winter above the ground but remains dormant below the surface until the start of the next season.

The Japanese knotweed was first brought to the UK in the mid18th century as an ornamental plant because of its broad green leaves and beautiful flowers. Unfortunately, most people realized that the plant grew pretty fast, thus throwing other plants out of the ecosystem.

It was also evident that the knotweed was damaging structures and other infrastructures.

Japanese knotweed reproduces during summer. The plant grows up to 10cm in a day; its deep-rooted system can grow up to 3 meters in depth. It can quickly become thick bushes if not controlled. There are several ways to remove the weed, as you will learn in this article.

Japanese knotweed in winter
Japanese knotweed stems in winter turn brown and brittle

What happens to the Japanese knotweed in winter?

The Japanese knotweed’s bamboo-like stems will begin turning brown and brittle during winter. This characteristic of the plant makes several homeowners believe that the plant is dead for good.

The Japanese knotweed is a perennial plant, and that explains its hibernation in winter. The sad news is that during this period, the plant’s rhizomes remain healthy as they lie dormant during the winter

What does Japanese knotweed look like in winter?

The knotweed’s green shovel-shaped leaves begin to turn brown and fall from the weed. The stems become hollow in early December. They eventually turn green similar to those of bamboo before they start decomposing. The stems will remain standing for a very long time.

Early shoots will be seen appearing as spring approaches. The stalks will be red or purple; they rapidly become green stems that grow speedily up to about 3 meters.

During winter the Japanese knotweed stems turn brown and die away
During winter the Japanese knotweed stems turn brown and die away

How long does the Japanese knotweed remain dormant?

The plant’s dead stems from the past summer growth can always be seen in vegetation that has lost its leaves and become dormant. They usually appear as the leaves fall towards the end of autumn, revealing the brownish canes that are about 3 meters tall.

The hollow stems may remain standing for about two years unless excavated or overthrown by the fresh string stems growing from beneath.

The dead stems are quite brittle and will often break into small fragments scattered all over the place. A fibrous network connects the crown and the rhizomes. The rhizomes measure between 0.5 to 10 cm wide.

The female Japanese knotweed does not spread by producing viable seeds. The UK Japanese knotweed spreads through rhizomes, stems, and crowns. These parts quickly grow into a new plant that spreads uncontrollably.

Should you get rid of Japanese knotweed in winter?

Besides its rapid growth in several setups, this knotweed has several risks on your property and that of your neighbour. The plant’s roots can quickly grow through the cracks of the house and weaken the whole structure; the rhizomes system can potentially damage the drainage system in several ways, including displacing them.

It becomes harder to sell your property at a deserving price when you have Japanese knotweed growing. It may even be not easy to sell the house without having ongoing professional treatment.

You will also need house insurance backup to guarantee the buyer that the job was done correctly. It is essential to understand that mortgage insurance will not let you get away with it, and this is why you need to deal with the weed as soon as you can effectively.

  • It is illegal to allow Japanese knotweed to spread to your neighbour’s land.  You may end up in court and pay hefty fines for the claims made against you.

It is recommended that you hire a professional knotweed removal company. The specialists can provide you with a particular management plan that will make it easier to eradicate the weed.

There are quite a several regulations about removing and disposing of the plant that you should be aware of before attempting to kill the weed.

An area being treated for Japanese knotweed which it to be isolated
An area being treated for Japanese knotweed which is to be isolated

What does the Japanese knotweed removal cost?

The Japanese knotweed removal cost will depend on the method of removal you intend to employ. It is worth noting that treating the weed yourself will almost not work.

Most property owners try to kill this weed using different techniques such as herbicides, digging up, and burning during winter, only for the plant to grow back.

Herbicide treatment done over some time by a knotweed removal specialist is relatively affordable. However, it takes several treatments up to some years to ultimately kill the Japanese knotweed.

Professional dig-out is the best option for those homeowners who might not prefer the long duration of herbicide treatments. This method extracts the stubborn root network to ensure that there is no fragment left in the soil that can into new plants.

This procedure may take longer depending on the size of the land that is infested. The knotweed removal technique is quite costly, but it is cheaper than how much you can lose on property depreciation.


Does Japanese knotweed die in winter?

The winter season will not eradicate the Japanese knotweed from your property; it can only slow its growth. The weed’s deep and extensive root system is deeply insulated in the soil and will be growing new shoots as soon as the weather is conducive.

The winter season gives you a chance to kill the plant as quickly as possible before the conditions are right again.

Want to know more?

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 –

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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