Japanese Knotweed Control

At Colin White Gardens we are fully trained and qualified contractors in the control of Japanese knotweed. We are based in South Hertfordshire and also cover North London. If you suspect you may have Japanese knotweed then get in touch to arrange a free no obligation site visit. We guarantee to beat any like for like price for Japanese knotweed control.

What is Japanese Knotweed?

Japanese knotweed was introduced from Japan in 1825 as an ornamental plant. The plant is not unattractive but its rapid annual growth and relentless spread, allows it to easily overwhelm other garden plants and cause damage to paths, drains and buildings.

In spring and summer, bamboo-like shoots grow to 2.1m (7ft) tall. Leaves are up to 14cm (5½in) in length and the creamy-white flower tassels produced in late summer and early autumn reach up to 15cm (6in). Japanese knotweed can grow at a rate of more than three feet per week. Although it does not produce seeds, it can sprout from very small sections of rhizomes. The rhizome is the part of the plant that is submerged under the soil.

The damage caused by its roots and stems costs the economy around £166 million every year in weed control and property devaluation. That’s why the Environment Agency describe Japanese knotweed as “indisputably the UK’s most aggressive, destructive and invasive plant”, and it can have a drastic effect on property values.

Is it Illegal to have Japanese Knotweed on my property?

No, It is not illegal to have Japanese knotweed in your garden, however an amendment to the Anti-social Behaviour, Crime and Policing Act 2014 includes Japanese knotweed and other invasive non-native plants such as Himalayan balsam and giant hogweed, to prevent them becoming a problem in your neighbourhood. If they have a “detrimental effect of a persistant or continuing nature on the quality of life of those in the locality”, the legislation could be used to enforce its control with the issuing of an ASBO! Therefore it is highly recommended that you should aim to control this plant. Under the provisions made within the Wildlife and Countryside Act 1981, it is an offence to cause Japanese knotweed to grow in the wild.

How to identify Japanese knotweed?

Mature Japanese knotweed canes can be identified by their distinctive purple speckle and stand as high as three metres tall. This is when they are fully grown by early summer. Towards the end of summer clusters of small white flowers appear, which are loved by insects for their nectar. In autumn, the leaves wither and fall off and the canes die back and go brown. The Rhizome (root)  has a dark brown bark and under this external layer, it is orange or yellow.

Why do we want to get rid of Japanese Knotweed so much?

Japanese knotweed has an extremely wide-ranging root system which can pose a serious threat to surrounding plants and have devastating consequences to building foundations and drains.

The biggest problems are caused when Japanese knotweed comes into contact with our homes and properties. The rhizome (or root) system can extend up to 3m in depth and 7m in all directions from each stem. These rhizomes can squeeze through the smallest cracks in masonry and concrete, meaning they pose a serious threat to building foundations and drains. This damage can make buildings structurally unsound and has led to panic among mortgage lenders.

Can I kill Japanese knotweed myself?

It is highly recommended that any attempt to control Japanese knotweed should only be carried out by trained and qualified persons. Due to the highly invasive nature of the plant, its complete eradication may require the use of potentially harmful chemicals that could put the user and the surrounding environment at risk if incorrectly applied.

How do we get rid of Japanese Knotweed?

The presence of knotweed on a property does not need to be a big deal but you do need to understand and be prepared for what you are taking on. Firstly we need to identify the scale of the problem. Don’t be fooled into thinking it’s a small problem if there is only a sprig or two, as it is the mass of the underground rhizome system that is important.
Japanese Knotweed treatment using herbicides is a tried and tested method of removing this plant. It is not instant and needs to be carried out by trained, qualified contractors who have an understanding about how the plant grows and how and when to apply the correct herbicides. The method of application is also important. Stem injection is an ideal method of application as it concentrates the chemical where it is needed and removes the risk of over spraying and unnecessarily killing other neighbouring plants. Because the applied herbicide is contained within the stem of the plant, it is also a very safe way to administer the chemical with extremely low risk potential to your family and pets. Most successful results from the use of herbicides occur from treatment in late summer and early autumn as the Knotweed is drawing nutrients, and therefore also the herbicide, down into its root structure before it dies back for the winter. It is imperative that during the treatment program, the Knotweed and its surrounding area should remain undisturbed. This is not only to ensure that each application of herbicide is as thorough as possible but also to prevent the Knotweed from spreading.

Japanese knotweed control – what should I do next?

If you have Japanese knotweed on your property, or if you suspect you may but aren’t sure, then get in touch to arrange a site visit from us. During our free no obligation visit, we can correctly and accurately identify the plants which you’re concerned about, and advise on the best course of action to ensure long term control and destruction of your Japanese knotweed.


Book a free no obligation visit

We will guarantee to beat any like for like price for Japanese knotweed control.