Japanese Knotweed begins to grow in the spring, from its underground rhizomes or roots which lie dormant over the winter months. Purple shoots, very reminiscent of asparagus spears begin to grow. These can grow up to 2cms per day and will quickly form large clumps of tall, bamboo-like hollow canes with purple spots, up to 2.1m tall. From these stems grow, light green, shield-shaped leaves. The leaves alternate along each side of the stem, producing an easily recognisable knotweed zigzag pattern. The knotweed flowers which are hanging clusters of creamy white flowers appear by late summer and grow to around 15cm in length.

It would appear that Japanese Knotweed is not as harmful to property as it had been imagined, it is still considered to be an invasive weed which will outgrow and strangle any other plants in the same area. Schedule 9 of the Wildlife and Countryside Act 1981 makes it an offence to ‘plant or otherwise cause Japanese Knotweed to grow in the wild’, either by fly-tipping or allowing it to spread from your garden into wild areas or neighbouring properties. All of this would tend to suggest that Japanese Knotweed is not an ideal plant to have growing in your garden and it is best to get rid of any which appears.

Carefully digging out small clumps of the plant is a feasible option for most gardeners, provided care is taken when removing the rhizomes or roots because the plant will regenerate itself from any small parts of rhizome remaining in the soil. Spraying with a proprietary glyphosate-based weedkiller is also an option, although it can take several applications, Glyphosate-treated knotweed will often regrow the following spring, although less vigorously, so treatment over three to four seasons may be required to completely kill Japanese Knotweed. The weedkiller is best applied to canes that have been cut, so that it can properly penetrate the plant and roots. Some brands carry specific instructions on how to control Japanese knotweed and these should be followed to ensure (eventual) success and ensure safety for yourself, pets and wildlife.

Under the Environmental Protection Act 1990, Japanese knotweed is classed as ‘controlled waste’, which means that it is illegal to add it to council-run garden waste bins or civic amenity sites. It should be disposed of at a licensed landfill site or left to dry and burned in your garden.

Larger clumps of Japanese Knotweed are much more difficult for the average home gardener to control or eradicate and serious consideration should be given to engaging the services of a specialist company whose business is to eliminate Japanese Knotweed. These companies have access to more powerful and effective weedkillers that may reduce the treatment period by up to half. They will also be better equipped to dig out the rhizomes or roots and will provide a plan for the eradication of the weed. Specialist Japanese knotweed contractors must be registered waste carriers to safely remove the weed from your property

Since 2013, homeowners selling their property are required to check their garden for Japanese Knotweed and declare any presence of the weed on the TA6 form, which is the property information form used for conveyancing. The TA6 form asks you to confirm whether or not your property is affected by Japanese Knotweed and, if it is, you will be required to provide a management plan for its eradication from a professional company.

If you are buying a property and the presence of Japanese Knotweed has been noted on the TA6 form, this often results in the mortgage lender seeking assurances that it will be eradicated before agreeing the mortgage. A management plan from a professional Japanese Knotweed eradication company, combined with a transferable guarantee, will usually satisfy the mortgage lender and allow them to move forward with your application for funds.

While most professionals will now agree that Japanese Knotweed is less harmful to strong structures such as buildings, than was mooted in the past, they will still agree that it can be potentially damaging to lighter structures or ground coverings such as paths or driveways. The advice from professionals would still be that it is probably wise to eliminate any Japanese Knotweed in your property to avoid any problems down the line. It is also worth noting that sometimes the perception of a problem can be worse than the reality and on that basis alone it is often better to eradicate the problem.

Before engaging with a contractor, it is always wise to check that they have the correct experience and insurances in place and are able to produce an eradication plan which would be acceptable to a mortgage lender if required.

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