At O'Driscoll Auctioneers we believe that informed buyers and well-prepared sellers make for smoother property transactions. Japanese knotweed is one of those issues that can cause real alarm when it is spotted in a garden, sometimes more than it deserves, and sometimes for good reason. It is an invasive plant that is now widespread across Ireland, and it is increasingly being raised during property sales. Here is what buyers and sellers need to know.
What is Japanese knotweed?
Japanese knotweed was introduced to Ireland as an ornamental garden plant, but it has since spread along roadsides, riverbanks, railway lines and gardens around the country. It grows remarkably quickly in spring and summer, forming dense thickets that can reach two to three metres in height. Its real strength lies underground, in an extensive network of roots known as rhizomes. Even a tiny fragment of rhizome or stem can grow into a new plant, which is why it spreads so easily and is so difficult to eradicate.
How to recognise it
In spring, look for red or purple asparagus-like shoots emerging from the ground. By summer, the plant develops hollow, bamboo-like stems speckled with purple, arranged in a distinctive zig-zag pattern, with large, flat, heart or shield-shaped leaves. In late summer and early autumn, clusters of small creamy-white flowers appear. In winter, the plant dies back to brittle brown canes, which makes it much harder to spot, so be particularly observant if you are viewing a property between November and March. Several native and garden plants can look similar, so if in doubt, ask a specialist to confirm.
Why it matters to buyers
Japanese knotweed is a regulated invasive species in Ireland. Under the European Communities (Birds and Natural Habitats) Regulations 2011, it is an offence to plant, disperse, or allow or cause the dispersal of the plant, and simply allowing it to spread can be considered an offence. Owning a property with knotweed on it does not break the law in itself, but as the owner you would be responsible for managing it responsibly and preventing it from spreading beyond your boundaries.
There is also the practical side. Knotweed can push through gaps and weaknesses in patios, driveways, garden walls, paths and drainage, and it can make gardens difficult to use. While its ability to damage the structure of a sound house is often exaggerated, it is certainly a nuisance that can be costly to treat. Its presence on a site has deterred some people from purchasing a property, and in Northern Ireland and England it has affected the availability of mortgages. Irish lenders do not all take the same approach, so it is worth checking with your lender early if knotweed is found.
What buyers should do
Walk the full garden and boundaries during your viewing, including overgrown corners, behind sheds and along ditches and hedgerows. Look over the boundary too, as knotweed on a neighbouring property or adjoining land can spread. Ask the seller directly whether knotweed has ever been present on or near the property, and whether any treatment has been carried out. If it has, request details of the treatment programme, the contractor used and any guarantee, and check whether that guarantee can be transferred to you. Your solicitor can raise the matter formally in pre-contract enquiries.
If you suspect knotweed but are unsure, consider commissioning a specialist survey before you commit. It is a modest cost compared with discovering an established infestation after you move in.
If knotweed is present
Discovering knotweed does not have to mean walking away. Treatment usually involves a specialist herbicide programme carried out over several growing seasons, or excavation and removal of contaminated soil. A professional treatment plan, ideally with a guarantee, can give buyers and lenders reassurance. Factor the likely cost and timescale into your offer, and discuss with your solicitor whether the seller should begin or complete treatment before closing.
Whatever you do, do not cut, strim, dig or compost it yourself. Disturbing the plant can easily spread fragments and make the problem worse, and contaminated soil and plant material need to be handled and disposed of carefully by specialists.
Advice for sellers
If you know or suspect knotweed is present on your property, deal with it early. Engage a reputable specialist to identify and treat it, and keep records of the work, including any management plan and guarantee. Be honest if asked about it. Concealing knotweed or giving inaccurate answers can lead to serious problems later, including potential legal claims from a buyer. A property with a professional treatment plan in place is far easier to sell than one where the problem has been ignored or hidden.
The bottom line
Japanese knotweed is a manageable problem when it is identified early and treated properly. Buyers who know what to look for, and sellers who address it openly, can prevent this persistent plant from derailing an otherwise successful sale.
If you would like to discuss buying or selling a property, contact us on 066 710 4038 or email info@odriscollpropertykerry.com or visit odriscollpropertykerry.com.
Disclaimer: This article is based on publicly available information and is intended for general guidance only. While every effort has been made to ensure accuracy at the time of publication, details may change and errors may occur. This content does not constitute financial, legal or professional advice. Readers should seek appropriate professional guidance before making decisions. Neither the publisher nor the authors accept liability for any loss arising from reliance on this material.
