JAPANESE KNOTWEED

Frequently Asked Questions by Home Owners

There are pictures of knotweed (Identifying Knotweed) showing it at different growth stages and times of the year. Alternatively, you can email a digital photo to knotweed(at)environet-uk.co.uk and we’ll identify it for free. To some people, the leaves and flowers may look attractive, but the underground rhizome or root system certainly is not!

The Victorians brought back cuttings from South East Asia in the late 19th century because of its attractive flowers. Unfortunately, it really is a case of Beauty and The Beast as the attractive plant runs riot and is very hard to shift.

That depends on how much knotweed is present and how quickly you need it eradicated. There are several methods available including landfill disposal, on-site burial, physical barriers, chemical treatment, and root extraction methods.

NEVER do that! Japanese Knotweed roots can go down at least 3 metres, as well as 7 metres sideways. If you don’t dig out every last little bit, it comes back. You must be extremely careful with any cut knotweed and extracted roots as these could re-grow and infest other areas in contravention of the law.

Sadly, there is a cost, and whichever method you select, the costs can range from around Ł2,000 to many tens of thousands of pounds. The faster you want it eradicated, the higher the cost. There are lots of variables that affect price, so please contact us first for an estimate or a detailed quotation.

Methods involving excavation are generally quick and not affected by seasons. Chemical herbicide methods can take three or more years if undertaken by a non-specialist. A professional specialist firm should be able to achieve eradication in one season. We often eradicate knotweed in a season and as long as we start before June, it should be complete by November.

That depends on the method employed. Chemical treatment is likely to be the least disruptive but plants close to the knotweed may be affected.

Knotweed is a major and growing problem in the UK because it is so hard to eradicate and spreads so fast. If knotweed is not treated, it continues to spread, its underground rhizome/root system will strengthen, and it becomes even harder and more expensive to eradicate in the future. If it’s located close to structural work, like walls, fences, drainage systems and paving, it can cause extensive damage. If it’s near your boundary and crosses over it, your neighbours could take legal action against you.

We’ve seen knotweed grow through concrete slabs and Tarmac, as well as through cavity walls, roofs, brick work and drains. You can see its destructive power on our Knotweed Video

Certainly, and especially if identified during the conveyance process. It’s relatively easy to overlook knotweed, particularly in winter when it looks like a dead plant, so property owners or buyers may not know it is there. If you’re buying a house, get your solicitor to ask the vendor specifically if knotweed is present. If they do not disclose its presence, you have legal redress.

What legal action can my neighbours take against me if knotweed spreads to their land?

If it causes nuisance to your neighbours, they could take out civil proceedings against you. However, if you take reasonable steps to fix or reduce the problem, they are unlikely to be successful.

Firstly, make sure your neighbour knows about the problem. It’s best to try and resolve it amicably, possibly by sharing treatment cost. Vertical root barriers can be installed to prevent encroachment, but as these need to be up to 3 meters deep, it’s likely to be an expensive process. You do have the option of legal redress if you can show that the knotweed originates from your neighbour’s property and is causing you nuisance. But going the legal route can be costly and won’t do much for neighbourly relations!

It takes an expert to make that judgment as the knotweed root/rhizome can remain dormant in the ground for a long time. If you employ someone to eradicate knotweed, rather than control it, there should be some form of validation or guarantee upon completion of the work.

I’ve noticed a few companies offering knotweed eradication guarantees. Are they worth the paper they’re written on?

That depends upon the company issuing the guarantee. We’ve seen some companies offering guarantees where the guarantee period is longer than the time the company has been in business. You need to check out their track record, take references, and if necessary, get a lawyer to check the guarantee wording. Environet has offered 5 year guarantees for its eradication treatment since 2004. These state that if the knotweed comes back, so will we at no further cost to the customer.

Is the cost of knotweed treatment or eradication, or any related damage repairs, covered under normal building insurance policies?

That depends on the exact wording of your policy, but our belief is that it’s unlikely to be covered. Insurance doesn’t appear to cover damage caused by gradual events, and we recommend you speak, very specifically, to your insurance provider about Japanese Knotweed.