When it comes to invasive plant species, Japanese knotweed is one of the most widespread and damaging you’ll ever come across. During the summer months, Japanese knotweed can grow as much as 2cm per day, quickly ravaging gardens and damaging homes and roads in its path. Did you know, the mere presence of Japanese knotweed can impact your house value by up to 10%?!
With so much to lose, we think it’s important that we spread the word and share our Japanese knotweed knowledge so that you can identify Japanese knotweed quickly if you do ever come face-to-face. We’ll also advise you on the best cause of action to take so you can regain control of the situation before it’s too late!
What does Japanese knotweed look like?Let’s not beat around the bush, to be able to identify Japanese knotweed accurately you need to know exactly what it looks like. Unsurprisingly, very few people are blessed with an encyclopaedic knowledge of plants, so identifying this worrisome weed can be a bit of a challenge.
Have a click around our Japanese knotweed specimen to see its key characteristics:
Distinct Features to look out for:
When leaves first emerge they are a bold burgundy colour and are rolled up around the tip of the offending asparagus-like shoot. As the leaves begin to mature, they unfurl to display a deep green colour and red veins. A fully-grown Japanese knotweed leaf is the green, love-heart shape we’ve come to recognise.
If you see any of these leaves appearing in your garden, we recomend enlisting the help of a Japanese knotweed specialist as soon as possible.
The main stems of the invader could easily be mistaken for bamboo, They’re dense, hollow and wood-like in texture. The smaller, younger shoots are not hollow, they’re very thin, malleable and grow in an iconic zig-zag pattern.
Like many plants, Japanese knotweed features a flurry of floral fronds during the summer months. The flowers themselves are an off-white colour and could almost be considered rather pretty. It’s a shame they’re the giveaway feature of a gardener’s nightmare.
The rhizome or root of the Japanese knotweed plant is the underground invader that allows Japanese knotweed to spread as far and fast as it does. The roots are a bright orange shade on the inside and a dark brown colour on the outside.
Identifying Japanese knotweed throughout the year
SpringDuring the spring, Japanese knotweed begins to make its presence known. Typically starting in mid-March, red and purple shoots will begin to appear and quickly bear rapidly growing leaves.
SummerIn the height of the summer, Japanese knotweed is in full swing. Bright and full, it appears green and leafy above ground, boasting creamy-white flowery clusters and purple-speckled stems.
AutumnAs the lush green of the summer turns to autumnal auburn, Japanese knotweed follows suit. Its leaves will turn a yellowy gold, while the stem will fade to a darker brown.
WinterAs temperatures drop, the wintertime design of Japanese knotweed becomes far less colourful. Brown and bare, the weed retreats back to its rooty rhizomes, leaving behind its woody stalks.
Knotweed or knotweed? That is the question...Thankfully, not all suspected cases of Japanese knotweed are the real deal. In fact, the villainous vine has many doppelgangers and most instances of suspected knotweed are merely a case of mistaken identity.
Before you start panicking or butchering your back garden, be sure you’re dealing with the real Nipponese knot. Here are a few similar shrubs to look out for.
Baring heart-shaped leaves like its Japanese twin, this also has a rapid growth spurt when it first appears in the springtime.
However, unlike Japanese knotweed, Bindweed isn’t capable of supporting itself and, instead, makes its vertical ascent by coiling itself around the stems of other standing plants.
It also boasts large flowers in the summertime, clearly differentiating itself from traditional Japanese knotweed.
Much like Japanese knotweed, Russian Vine has similar looking leaves and flowers, while it is also fast-growing.
On the other hand, it is also similar to Bindweed in that it relies on other plants to grow upward, twisting and climbing around the stems of taller, more solid vegetation.
The most widely known of its contemporaries, bamboo grows tall like knotweed and also has visible nodes on its stem, making the two very similar in appearance.
That being said, bamboo stems are considerably denser than its Asian brethren and boast a strong sturdiness lacking in Japanese knotweed. Bamboo leaves are also notably narrower and longer.
Part of the same family, Broadleaf Dock shares numerous characteristics with Japanese knotweed, from its arrangement of leaves to the spiky shape of its flowers and stems.
However, this plant is typically shorter than Japanese knotweed and contains a foamy substance in its stem, clearly visible when cracked open.
What to do if you suspect Japanese knotweedIf you’re fairly certain you’ve come across this invasive crop then you need to get a professional second opinion. Someone who’s used to dealing with Japanese knotweed on a regular basis will be able to confirm the plant’s identity, determine the severity, and advise you on the best course of action.
Get in touch with the Taylor Total Weed Control team if you'd like us to perform a free, no-obligation survey of your suspect shrub.
We offer a range of Japanese knotweed treatment plans, as well as a Japanese knotweed insurance backed guarantee, so that your home and garden can recover quickly.
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