Japanese Knotweed in the Winter – Does it Die?

Japanese knotweed can be a real menace. It grows rapidly and is very difficult to eradicate without professional help. In the UK, it has the label of an invasive species. It has been known to damage buildings, grow through foundations, suppress native plants’ development around it, and knock thousands off of property prices.

The spread of Fallopia japonica (the Latin name of Japanese knotweed) has reached epic proportions and more cases are identified every day. It can now be found in many parts of London, Merseyside, Bristol, and Lancashire, and is spreading along corridors from Nottingham to Sheffield and Swansea to Newport.

Japanese knotweed grows most rapidly during the summer months, but that doesn’t mean it’s not a problem at other times of the year. It’s easiest to spot and identify Japanese knotweed in warmer months, but in winter, you can still spot it and it still continues to spread.

What Happens to Japanese Knotweed in Winter?

As temperatures start to plummet, in winter, Japanese knotweed looks like it’s dying off. The vigorously growing bamboo-like canes turn brown and look like they have no life in them. The canes appear spindly and lose their leaves.

Don’t be fooled by its brown, brittle state. It remains very much alive and is just lying in wait for the spring when it will emerge bigger and stronger with fresh new shoots. The first signs of life will be red or purple shoots that look very much like asparagus.

How to Identify Japanese Knotweed in Winter

When trying to identify Japanese knotweed in winter, here’s what to look out for:

• Dry, brittle canes a metre or so in height
• The canes may cover a large area
• Other vegetation around the area has died or gone completely
• New shoots, which appear like small red or green lumps on the ground, may form at the end of winter.

Download our PDF on identification

Does Japanese Knotweed Die in Winter?

No, Japanese knotweed does not die in winter, instead it becomes dormant above ground to preserve energy. In winter, Japanese knotweed spreads underground through its root system, waiting for warmer weather where it can create new shoots above ground.

Methods for Identifying Japanese Knotweed in Winter

During the winter, Japanese knotweed withdraws back into its rhizome, and therefore identification can still continue. But how do professionals like Japanese Knotweed Specialists accurately identify knotweed in the winter?

Japanese Knotweed Dog Detection Surveys

We are able to use specially trained dogs to sniff out Japanese knotweed all year round. By using dogs that are often used for bomb or drug detection and training them to smell the rhizome systems of knotweed, they can spot knotweed even in the winter months.

These highly trained dogs can identify knotweed that is underground, dormant or in hard-to-reach places that humans may not be able to get to.

How Do You Remove Japanese Knotweed in the Winter?

In winter, removal of knotweed can be easier, as there is less overground vegetation to contend with. It also allows us clear visibility of the extent of the spread, as there are no leaves on the canes to mask other canes.

A professional Japanese knotweed removal company like ourselves will be able to dig the crowns and rhizome network out. It is by far the most effective option for removing the risk of knotweed affecting a property. A large amount of waste will be produced, but it is the preferred method for landowners who want to return their land to a knotweed-free state as quickly as possible.

Care has to be taken because there is a risk of breaking off part of the crown attached to the network of rhizomes underground. If this happens, it can trigger new growth and lead to new knotweed areas appearing in the location. Ideally, the stems should be cut at least 10 centimetres above the crown of the knotweed stem.

Burning is another option, depending on local by-laws. If this method is used, you must scrape up all material and deposit it back onto the area. When removing Japanese knotweed, take care to clean your boots and tools when you’ve finished. This is to make sure you’re not transporting any fragments across your garden.

What Are Your Responsibilities With Regards to Japanese Knotweed in Your Garden?

Japanese knotweed is included as an invasive non-native plant in an amendment to the Anti-Social Behaviour, Crime, and Policing Act 2014 and Wildlife and Countryside Act 1981 section 114 (2) (WCA 1981) While it’s not illegal to have knotweed in your garden, you are not allowed to let it have a “detrimental effect of a persistent or continuing nature on the quality of life of those in the locality.”

As knotweed spreads underground in winter, it can be easy to think that you can let it be in winter and deal with it in spring, but by then, it may be too late. Knotweed can grow and spread year round, so the best course of action is to hire a specialist Japanese knotweed contractor, such as Japanese Knotweed Specialists, who can advise on the best course of action, regardless of the time of year.

If you allow it to spread into neighbouring properties or land, you could face prosecution. It’s also worth remembering that it is classed as ‘controlled waste’ under the Environmental Protection Act 1990.

Here at Japanese Knotweed Specialists, we can provide a site-specific management plan that will allow us to tackle Japanese knotweed in winter and any other time of the year. We also offer our customers an insurance backed guarantee as well.

Japanese Knotweed Doesn’t Disappear Just Because It’s Winter

Just because you can’t see the Japanese knotweed doesn’t mean it’s disappeared, never to rear its ugly head again. On the contrary, the extensive rhizome root system will be very much alive and spreading in your garden or grounds, ready to sprout at the sign of warmer weather.

Do You Suspect That You May Have Japanese Knotweed?

We can provide identification services year-round, as well as helping you to create a management plan that encompasses any affected areas.

For more information on Japanese knotweed removal, identification or just advice, please don’t hesitate to contact us at any time of the year.