Knotweed identification

What is

Japanese knotweed (Fallopia Japonia) is a hardy bamboo like plant that was imported from Japan in the 1850’s and was introduced to Britain as an ornamental plant and for cattle feed.

Although an attractive plant, the Environmental Agency has described knotweed as “indisputably the UK’s most aggressive and invasive plant”. This is because the stem growth is renewed every year from the deeply penetrating rhizomes (underground roots) and the fact that knotweed has no known predator in the UK.

Knotweed easily overwhelms other garden plants. It is a perennial plant, meaning its appearance changes with the seasons. It starts with small fleshy roots in the Spring and can grow up to 10cm per day and over 3 metres high in the spring and summer, before dying back to brittle, leafless canes in the winter, where it is less identifiable. Knotweed can spread from very small sections of root at an alarming rate and can cause problems to foundations and drainage of a property if left untreated.

Knotweed is present within nearly every 10sq km of the UK and continues to grow at an alarming rate. So whether you are in Devon, London, Birmingham, Newcastle or beyond, The Knotweed Experts are able to use our experienced, local contractors to provide you with expert advice and treatment.

Japanese knotweed

The appearance of knotweed changes dramatically over the seasons and our handy guide below may help you to identify whether you have knotweed growing on your land.


Red buds begin to emerge from the base of the plant (the crown) during February-March and develop in to small fleshy deep red/purple asparagus type shoots and start to grow rapidly. Maturing canes are hollow, somewhat like bamboo and are identified with red speckled characteristics with curled red veined leaves. These leaves start to turn dark green and unfold towards end of Spring.


The combination of sheer height and density of Japanese knotweed in the summer makes the plant easily identifiable. At an average of between 2-3 metres high in full bloom, the spade shaped leaves and spiky stems with creamy white flowers make the plant appear attractive. However, the exponential growth above ground masks the speedy way in which the underground rhizomes are expanding.

Knotweed is a good source of nectar and may attract bees and other pollinating insects and full bloom begins around late August.


The appearance of Japanese knotweed in autumn will have very similar traits as in late August, as the flowers will be in full bloom until October. Towards the end of October and through to November, the leaves will start to wilt and turn yellow and the stems will become dark brown in colour and start to become dormant.


The leaves have fallen and the dark brown canes will appear to be decomposing and may collapse and intertwine.  New seasons shoots may already begin to appear under the dense brittle canes. Whilst in winter, knotweed remains dormant above ground, below ground the rhizomes are still present and may continue to grow.

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Our knowledge and long-term experience allows us to create an efficient and cost effective Japanese knotweed management plan suited to your needs. Although we have a proven process, each treatment plan is designed to best deal with each individual case, therefore making sure the plan put in place assures complete removal of the plant.

How to

In domestic situations, knotweed can have serious implications to your property and land.

The rapid growth of the rhizomes underground can cause extensive damage to patios and pavements, drainage systems and pose a severe risk to the foundations of your home. Whilst it is not illegal to have knotweed on your land, allowing it to encroach on your neighbours property without proactively trying to control the weed can constitute private nuisance under common law. Knotweed is governed by many strict guidelines and if not disposed of properly and safely by a PCA- approved licensed contractor, can leave you liable to prosecution.

Knotweed can impede the sale and/or affect the value of your property significantly. Approaching a licence mortgage compliant contractor like The Knotweed Experts means that your knotweed is treated and eradicated along mortgage compliant guidelines and will be backed by up to a 10 year guarantee.

How it is

Knotweed removal methods are not as simple as cutting back the foliage – the vast network of root systems below ground will also require treatment.

Treatment depends on how vast the knotweed is, what damage the root system has done below soil and the location of the weed.

Using our experience and honest approach, we can work with you to undertake the most effective and practical course of treatment at a fixed fee, with no hidden extra charges and the amount of the survey deducted from treatment costs. Our management plans will cover the length of your treatment and may also include periodic surveys to safeguard that your property stays weed free.

Some of ways of removing Japanese knotweed and treatments we use effectively are:

Herbicide foliage sprays

A foliage and root system herbicide spray is a cost effective option for the removal of Japanese Knotweed. Generally used on residential sites or sites that are not subject to strict Japanese knotweed deadlines. Once the herbicide spray is absorbed down to the rhizomes for the full length of the treatment plan then no regrowth will form.

Dependent on many factors, using herbicide treatment can take between 3-5 Growing Seasons. This is the most cost-effective treatment available.

Your guarantee will be issued from day 1 of proceeding with the treatment plan. Subject to our T’s & C’s.

Stem Injection

Stem injection is a method of applying a concentrated dose of herbicide directly in to the stem of the plant, via a needle directly in to the stem, trans-locating the herbicide through the roots and rhizomes.

Stem Injection is less risky to the environment, as it reduces the risk of spray drift, which could cause harm to other plants and nearby water.

Stem injection can be completed in all weather and further treatment may be required until no further regrowth is observed.

Knotweed barrier

Knotweed barriers are used to prevent the spreading of the weed. If laid correctly by a licenced contractor like The Knotweed Experts, the membrane is laid underground and contains the rhizomes. Knotweed membranes are particularly effective to help stop the spread of the roots on to neighbouring land or to stop the Knotweed coming back onto your property, they are usually used alongside other removal treatments.

Soil sifting and screening

The Knotweed Experts will sift through all of the soil and remove the Knotweed rhizomes, leaving knotweed free soil on site. Soil sifting is a popular course of treatment, as there is reduced waste to move from site and is an extremely effective treatment.


Generally used for larger land projects but can be used on residential sites, excavation is a quick and effective process for knotweed removal. Infested waste can be disposed of on site where able to, or the waste can be removed and located to a licenced landfill site.

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