Japanese knotweed’s invasive nature is not to be underestimated. This highly invasive plant can quickly take over an area, damaging property and disrupting ecosystems.
If you have Japanese knotweed on your property, it’s important to take action immediately. This weed can quickly grow out of control and cause significant damage.
Our guide will show you how to identify Japanese knotweed, as well as how to remove it safely and effectively. We’ll also provide tips for preventing future infestations.
Japanese knotweed can cause many problems
Fallopia japonica, also known as Japanese knotweed, is a common garden weed. Its invasive roots and bamboo-like stems with huge, heart-shaped leaves can soon encroach on the available growth space. The difficulty of removing Japanese knotweed has earned it a reputation as one of the most problematic garden weeds.
Homeowners should be especially cautious, as the appearance of Japanese knotweed in the garden might deter potential buyers and lead to mortgage applications being denied by banks.
Victorian plant hunters brought Japanese knotweed to Britain in the 1800s. It was admired for its exotic appearance, heart-shaped leaves, and lovely flowers, which resembled those of astilbe or goatsbeard, and was grown as an appealing decorative garden plant. Its rapid growth, on the other hand, quickly rendered it unsuited for garden cultivation.
It is currently illegal to cause Japanese knotweed to flourish in the wild, whether through fly-tipping or allowing the plant to escape your garden.
More information about eliminating Japanese knotweed can be found here:
What is Japanese knotweed?
Fallopia japonica, sometimes known as Japanese knotweed, is a weed that has spread throughout Japan. It may swiftly take over a space with its creeping roots and long, bamboo-like stalks.
Japanese knotweed has 1m-deep roots that are extremely difficult to dig up, and the plant may grow through brickwork and pipe cracks. Allowing Japanese knotweed to spread onto other people’s property or into the wild is against the law.
How to identify Japanese knotweed
Japanese knotweed is a herbaceous perennial weed that grows in big clumps of up to 2.1m tall bamboo-like canes with purple patches. Light green heart-shaped leaves occur alternately on these stems, followed by dangling clusters of creamy white blooms. The flowers are 15cm in length and the leaves are 14cm long.
The plants go dormant in late autumn, and the canes die and lose their leaves. The dead canes are frequently left standing, and it can take years for them to decay.
Look for fleshy, reddish shoots developing on their own or among the dead bamboo-like canes in the spring. These shoots produce new canes, leaves, and flowers.
Plants that are often mistaken for Japanese knotweed
Other plants, such as the Russian vine, Fallopia baldschuanica, can be confused with Japanese knotweed. Russian vine has thinner, almost-arrow-shaped leaves and a considerably more scrambling behaviour than Japanese knotweed, despite the comparable blooms and leaf shape. The absence of tall stems is the most noticeable distinguishing characteristic.
Leycesteria formosa, often known as Himalayan honeysuckle, is sometimes confused with Japanese knotweed. On closer study, though, you’ll see that the Himalayan honeysuckle has opposite leaves, not alternate leaves (the leaves emerge at the same position on either side of the stem).
The flowers, which are tall, purple, and white, are also quite diverse. Persicaria species have similar-shaped leaves to Japanese knotweed, but they are narrower and lack the bamboo-like growth of Japanese knotweed.
How Japanese knotweed causes such problems
Japanese knotweed can emerge from even the tiniest root fragments. It’s a fast-growing plant that can soon spread over your garden and into neighbouring gardens. Its roots have been known to take advantage of cracks in brickwork and plumbing, and it has even been known to cause damage to highways.
If you see Japanese knotweed growing near your house, you should get rid of it right once because it can harm your home’s foundations.
Japanese knotweed can also sprout from seeds. This means that if Japanese knotweed is growing in a neighbouring garden, it will very certainly invade yours, either through its spreading roots or through seed. Keeping an eye out for early symptoms of development can help you swiftly eradicate Japanese knotweed and prevent subsequent outbreaks.
Because of its invasive nature and tendency to out-competing all plants growing around, Japanese knotweed poses problems in gardens. It is, however, an issue in the wild.
Unfortunately, Japanese knotweed has escaped and/or been thrown in the wild, where it multiplies swiftly and poses a hazard to natural ecosystems. Along with railway banks and train stations, as well as canal towpaths, it’s a regular sight. It’s thought that the wind created by passing cars aids in the spread of Japanese knotweed seeds.
Japanese knotweed and the law
It is illegal to cause Japanese knotweed to grow in the wild, either by fly-tipping or permitting the plant to escape the limits of your garden, according to Schedule 9 of the Wildlife and Countryside Act 1981.
While it is permissible to cultivate Japanese knotweed in your garden, it is unlawful to allow it to spread into wild areas or neighbouring gardens, thus eradication or at least management of its spread is recommended. Furthermore, if you’re selling your home, you’ll need to get rid of it.
Since 2013, homeowners selling their homes have been required to inspect their gardens for Japanese knotweed and disclose its presence, as well as offer details on an eradication strategy.
If Japanese knotweed has been discovered growing on the property you’re buying, your mortgage lender may want evidence that a management plan for its eradication is in place. It’s crucial to check for yourself, regardless of whether it’s been stated or not, to avoid any complications later on.
Japanese knotweed is classified as “controlled waste” under the Environmental Protection Act of 1990. This makes it illegal to put it in compost bins at home or in council-run garden trash bins. It is permissible for you to burn the rubbish (ideally after allowing it to dry). You’ll have to dispose of it at a permitted dump site if you don’t want to do it yourself.
If you find Japanese knotweed being dumped illegally in the wild, contact the Environment Agency.
Ways to remove Japanese knotweed
Small patches of Japanese knotweed are relatively easy to manage and can be dug out or sprayed with weedkiller by the home gardener. To handle huge clumps, however, we recommend hiring a skilled, professional contractor. Using specialists has the advantage of generating risk reports and treatment programmes that include a guarantee of total eradication, which is usually recognised by mortgage lenders.
Traditional methods of removing Japanese knotweed
The best option here is a glyphosate-based weedkiller, but keep in mind that it may take numerous applications over up to four seasons to entirely eliminate Japanese knotweed. It’s better to apply it to cut canes so that the weedkiller can reach the plant’s roots completely. Specific tips on how to control Japanese knotweed can be found on some brands’ websites.
To achieve the most effective control while minimising dangers to yourself, pets, and animals, make sure you follow the directions carefully.
Knotweed that has been treated with glyphosate will often reappear the following spring, though considerably less strongly. It’s critical to apply a second treatment to this growth.
Organic methods of removing Japanese knotweed
Due to its propensity to regenerate from small pieces of root and the complications surrounding its disposal, digging the plant out of the ground may cause more problems in the long term. It is feasible to gradually weaken the plant by removing all leaves as they grow, effectively stopping the plant from photosynthesis.
This strategy, however, can take a long time to work — you’ll need to check the plant at least once a week and pluck new leaf buds as you see them.
10 ways to prevent future infestations
Japanese knotweed is an invasive plant that can quickly take over an area, crowding out native plants and damaging infrastructure. There are a number of ways to prevent future infestations of Japanese knotweed, including:
1. Monitor the perimeter of your property for any signs of the plant and remove it immediately if you find it.
2. Encourage your neighbours to do the same.
3. Installing a fence around your property to keep the plant from spreading into your yard.
4. Removing any debris or objects that could provide a place for Japanese knotweed to grow.
5. Using herbicides to stop new seedlings from sprouting up.
6. Installing weed-blocking fabric into your yard.
7. Keep any soil that may be carrying knotweed seeds out of your garden, such as by raking up leaves in autumn and disposing of them at a facility that provides free mulch or through a commercial service.
8. Use clay pellets instead of mulch to keep weeds from sprouting up in your yard.
9. Prevent soil erosion by planting native plants and covering the ground with wood chips rather than other types of materials, which could allow knotweed seeds to become airborne and spread more easily.
10. Hiring a professional company to take care of the Japanese knotweed problems you have.
Japanese knotweed is a noxious weed that can quickly spread throughout your property and cause serious damage. With the right equipment, identification knowledge, and treatment plan you can remove it from your home without too much trouble.
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Knotweed Removal, UK
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