You probably already know that Japanese knotweed is a big problem here in the UK. But can this invasive plant species be found all over Great Britain, or is its growth concentrated in specific areas?
Photo by dankogreen (Flickr)
According to gardenorganic.org.uk, Japanese knotweed was initially "most prevalent in South Wales, perhaps due to the moist climate, but it is now widespread throughout the UK". As we mentioned in a previous blog post, South Wales is still - to this day - one of the UK's key Japanese knotweed hotspots, alongside cities like London and Bristol.
Japanese Knotweed Removal in South Wales >>
The term "invasive species" may not sound very threatening, but these invaders, both large and small, can and do have devastating effects on wildlife and communities across the world.
Invasive species are one of the most threatening problems to native wildlife, with approximately 42% of endangered species at risk as a result of invasive species. Endangered species aren't the only things that are at risk due to invasive species, however, with economies and human health also susceptible to feel the effects. The impact that invasive species have on our natural ecosystems and economy cost billions each and every year, with many of our recreational, agricultural and commercial activities heavily reliant on healthy native ecosystems.
Salt is very versatile - it can make virtually any meal taste better - but sadly, there are some problems that salt can't solve.
You may have heard that salt can be used to kill garden weeds, and there is some truth to that. Applying salt to an unwanted plant can cause the plant to dehydrate and ultimately die.
But should you actually try this? The RHS don't recommend it: "The use of bleach or salt to kill weed on paths and drives is strongly discouraged, as this can cause pollution and damage plants."
Besides, Japanese knotweed is no run-of-the-mill garden weed. It takes a lot to eradicate this invasive species once and for all - a mere sprinkling of salt just won't do it!
The Environment Agency's Japanese knotweed code of practice was originally published in 2006. After several revisions, the publication was withdrawn on 11 July 2016:
"This guidance has been withdrawn from use because the Environment Agency no longer provides best practice guidance."
However, the Property Care Association - the UK's trade association for specialists who deal with problems that affect buildings - published its own code of practice in April 2018.
(Note that the PCA's code of practice is NOT the law. It is merely a document that explains the best practices for controlling Japanese knotweed. If you're looking for official government guidance and legislation, see gov.uk's page on how to stop invasive plants from spreading.)
Summer's here, which means that Japanese knotweed plants in the UK are currently in the most aggressive phase of their growing cycle (see When Does Japanese Knotweed Grow? for more information on that).
Photo by Leonora Enking (View Original)
Japanese knotweed is at its most visible during the summer, so now is the time to have a look outside and make sure this invasive plant species is not growing on your property.
What is Japanese Knotweed? Identifying Japanese Knotweed
Here are five common Japanese knotweed signs to watch out for...
Japanese knotweed can be found all over the UK. Many British homeowners have had problems with this invasive plant species, but it is also abundant in the wild - on roadsides and near railway lines, for example.
What is Japanese Knotweed?
Ecologists are already employing all sorts of different tactics to get the UK's Japanese knotweed problem under control (perhaps you remember our recent blog post about the sniffer dogs who'd been trained for this purpose). But it's hard to defeat an enemy whose location is unclear, and one big hurdle in the fight against Japanese knotweed is the fact we don't know exactly how widespread the plant is.
SHORT ANSWER: Japanese knotweed can grow up to 10cm per day during the summer months.
Japanese knotweed has a reputation for fast, aggressive growth. Not only can this invasive plant species grow through cracks in brickwork and concrete, it can do so with rather frightening speed!
Japanese knotweed's growth rate depends on the time of year. As we've discussed previously (see When Does Japanese Knotweed Grow?) the plant goes dormant during the winter months, then re-emerges in the spring.
Summer is when the plant hits its top growing speed. Japanese knotweed loves warm weather, and it has been known to grow by as much as 10cm per day during the summer months!
Like an unwanted house guest, Japanese knotweed can be difficult to get rid of. Patience and persistence are key to getting the job done properly.
Photo by Leonora Enking (View Original)
As we discussed in our blog about Japanese knotweed's growing cycle, this invasive species may appear to die off completely during the winter months. But appearances can be deceptive.
When selling a property in this country, you have to fill out a TA6 form, which includes this question:
Is the property affected by Japanese knotweed?
☐ Not known
It's important for sellers to answer this question truthfully, because Japanese knotweed is an invasive species that can grow very rapidly and may cause structural damage if it grows through cracks in a wall or foundation. Homes with Japanese knotweed are notoriously difficult to sell, and getting rid of the plant can be an long and costly process.
READ MORE: Selling a House with Japanese Knotweed
Unfortunately, there are some dishonest people out there, and sellers will occasionally feign ignorance of their Japanese knotweed problem for fear that it will complicate the sale. So what should you do if you've discovered Japanese knotweed on your property...and the seller didn't tell you about it?