Japanese knotweed, or Fallopia Japonica was first introduced to the UK by German botanist Philip von Siebold.
Following his travels in Japan, Siebold launched Japanese knotweed as an ornamental plant for commercial sale and botanical cultivation. It was considered highly decorative, and it made its first appearance in Kew Gardens in 1850. Japanese knotweed was praised for its fast growth in areas that needed a quick makeover, like railway sidings. So, with its lush foliage and pretty white flowers, it’s easy to assume that this is a valuable addition to your border rather than the aggressive problem that we now know it is.
In this blog, we’ll investigate some mistaken plants that look like Japanese knotweed and learn about some distinguishing features of Japanese knotweed. Correctly identifying highly invasive plants like Japanese knotweed could save you from incurring a considerable bill to treat the invasion.
The best way to correctly identify Japanese Knotweed is to contact an experienced professional like The Knotweed Specialist. If you’re in any doubt that you have Japanese knotweed within your grounds, send us a WhatsApp image, and we’ll get back to you straight away.
What Does Japanese Knotweed Look Like?
The first step in tackling an invasion is to understand how to identify Japanese knotweed and recognise the small white flowers, large spade-shaped leaves, and strong woody stems. Japanese knotweed has several identifying features, depending on the season. To correctly identify and avoid mistaking plants that look like Japanese knotweed, it’s helpful to learn what it looks like depending on the time of year.
Spring
Pink buds erupt at ground level from the underground rhizomes in Spring. From the Japanese knotweed shoots, reddish-purple stems grow rapidly, forming fat asparagus-like spears. The stems resemble bamboo shoots but are distinguished by their reddish-purple speckles.
Summer
By summer, the canes will have grown profusely into dense thickets, reaching their full height of around 3 to 3.5m by late summer. Large shovel-shaped leaves form a concentrated canopy, starving nearby plants and wildlife of sunlight. Clusters of creamy white elongated flowers form at the tips of the stems and are produced towards the end of summer and early Autumn.
Autumn
As Autumn progresses, the leaves turn yellow and orange and begin to wilt and fall. At this time of year, the vibrant red stems may be more visible and easy to identify. Gradually, the hollow stems turn brown, and the leaves and flowers die.
Winter
The plant dies back in the winter, leaving masses of dry, brown stems covering the ground. Underneath the ground, the Japanese knotweed rhizome system remains active, storing nutrients and enabling the plant to spread underground.
The Knotweed Specialist is experts at tackling invasive plants. Our service begins with identifying the plant. We will then conduct a comprehensive survey and produce a management plan to effectively treat, remove and dispose of your infestation.
Japanese Knotweed Lookalikes
Many plants are mistaken plants that look like Japanese knotweed, but let’s take a look at the top contenders in the Japanese knotweed lookalike competition:
Russian Vine or Fallopia Baldschuanica is perhaps the most like Japanese knotweed and is also an invasive plant. It is fast-growing, with tiny white or pink flowers and heart-shaped leaves. The stems are woody and thick, growing up to 10 meters tall. Unlike Japanese knotweed, the Russian Vine wraps its vines around nearby plants and structures.
Dogwood or Red Cornus has an abundance of oval-shaped leaves and white flowers. In the Autumn, it reveals red stems, making it a very close lookalike to Japanese knotweed. Its distinguishing feature is the leaves that grow directly opposite each other, whereas Japanese knotweed leaves alternate up the stem. Dogwood is not invasive in the UK.
Himalayan Honeysuckle and Japanese knotweed have hollow stems and alternately shaped leaves. However, the leaves of the Honeysuckle are more pointed, and it has pinky-purple flowers.
Bindweed or Convolvulus Arvensis is a fast-growing perennial vine that can take over large areas and suffocate nearby plants but is not considered as damaging as Japanese knotweed. It is a climbing plant with heart-shaped leaves and white trumpet-shaped flowers, and it does not have strong woody stems like the Japanese knotweed. Its aggressive growth means Bindweed should be controlled to prevent it from taking over.
Himalayan Balsam or Impatiens Glandulifera is widely invasive in the UK. It has lush green leaves on stems that grow up to three metres, but unlike Japanese knotweed, its flowers are pink-purple. Himalayan Balsam causes damage to local ecosystems by outcompeting local plants. Controlling the plant before it seeds is key to managing infestations.
Giant Knotweed grows taller than Japanese knotweed and has considerably larger leaves. It is part of the Fallopia family and shares very similar traits to Japanese knotweed. It is a perennial that dies down in the winter. It is seriously invasive because it spreads quickly and takes over local plants and wildlife. There are legal requirements regarding the control of Giant knotweed.
The Knotweed Specialist is PCA certified and have considerable experience tackling Japanese knotweed, Giant knotweed, Himalayan Balsam and Bindweed invasions nationwide. Don’t take chances if you think you may have an invasive species within your boundaries, call the experts and avoid costly mistakes.
