If you have Japanese Knotweed in your garden you should take action without delay.
The longer you leave Japanese Knotweed, the more it will spread, and ultimately may cause damage to your property.
BEWARE – some lenders now refuse mortgages on residential property infested with Japanese Knotweed! This may affect the value of your property.
You should identify the source of the infestation – if it is coming from adjoining land see Japanese Knotweed – Encroachment from Adjoining Land.
If all other attempts to get the owner of the adjoining land to take action fail you may have a claim under civil nuisance. See Japanese Knotweed - A legal perspective.
You should start a treatment programme as soon as possible. Usually, herbicide treatment is the most cost effective method, especially where time permits. The aim is to kill ALL underground rhizome – if you don’t you’ll continue to get re-growth for years to come.
Inappropriately applied herbicide can induce rhizome dormancy. The plant is not killed, and simply remains in a dormant state for a period of time until re-growth occurs.
Herbicides must be used with care for obvious safety reasons. Herbicide treatment can affect non-target plants both in your garden and in adjoining land, so you may feel this is something best left to the experts.
Frequently Asked Questions by Home Owners
I think I may have Japanese knotweed. How can I identify it correctly?
Take a look at Identifying Knotweed, which shows photographs of Japanese Knotweed at different growth stages and times of the year. Alternatively, email a digital photo to us and we'll identify it for you. To some people, the leaves and flowers look attractive, but the underground rhizome or root system certainly is not!
Is Japanese Knotweed poisonous?
No - in fact, you can find internet recipes containing knotweed! It contains a substance called resveratrol, and is used in anti-aging supplements.
Where did Japanese Knotweed come from?
The Victorians brought back cuttings from South East Asia in the late 19th century because of its attractive flowers. If its in your garden, it’s either spread or encroached from adjoining land, or soil containing rhizome has been deposited on your land. It does not spread by seed in the UK. .
I've got knotweed on my property. How do I get rid of it?
That depends on how much knotweed is present and how quickly you need it eradicated. There are several methods available. Herbicide treatment is likely to be the most cost effective and least disruptive, but other options such as Xtract™, Dig & Dump and use of root barriers for containment may also be available to you.
Can't I just cut it down and dig up the roots like any other weed?
That’s not advisable! Japanese Knotweed grows deep into the ground, typically 2m deep. If you don't dig it all out, it comes back. You must be extremely careful with any Japanese Knotweed you do dig out. Both the green vegetation and the rhizome system is likely to re-grow and infest other areas. If you allow this to happen anywhere other than your garden you will be in contravention of the law.
How much does it cost to treat knotweed?
As a general rule, the faster you want it eradicated, the higher the cost. There are lots of other variables that affect price, so please contact us for a budget cost or a detailed quotation.
How long does it take to get rid of it?
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 a single season, if conditions are right. Treatment should commence prior to May for completion in October.
Will the treatment be disruptive?
That depends on the method employed. Chemical treatment is likely to be the least disruptive but non-target plants close to the knotweed may be affected.
Knotweed sounds like a big problem. What happens if I ignore it?
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 crosses your boundary into adjoining land, your neighbours could take legal action against you.
What sort of property damage could be caused?
We've seen knotweed grow through concrete slabs and asphalt, as well as through cavity walls, roofs, brick work and drains. You can see its destructive power on our Knotweed Video
Can knotweed affect the value of my property?
Certainly, and especially if identified during the conveyance process. Several leading mortgage companies currently refuse to offer mortgages on property infested with Japanese Knotweed. 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 knowingly do not disclose its presence, you may have legal redress for mis-representation.
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.
If we treat it, how can we be sure it's dead?
It takes an expert to make that judgment as the knotweed root/rhizome can remain dormant in the ground for a long time. In reality, it is impossible to verify with 100% certainty that all rhizome is dead, unless you physically excavate all infested soil and check every piece of rhizome. Clearly that is impractical. 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. Where our Xtract™ method is used, we offer extended guarantees for 20 years.
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 if your property is being damaged by Japanese Knotweed.
