Invasive plants

Know what’s growing in your garden

Not every homeowner is a botanist. However, when it comes to selling or purchasing a house it pays to know what is growing in the garden. The presence of certain invasive plant species, such as Japanese Knotweed, can heavily impact your property value and has the potential to impede the sale of your home.

By booking a Home Survey you can save yourself some additional stress. Our surveyors are trained to recognise signs of invasive plants that could cause difficulties in the sale or purchase of your property.

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Japanese Knotweed

Japanese Knotweed is the most publicised of the invasive plant species in the UK. It is an herbaceous perennial originating from Japan with strong roots that can grow up to 20 metres underground. This makes it extremely difficult and costly to remove. If left untreated it has the perceived risk to cause substantial damage to property grounds and infrastructure.

When discovered, the eradication of Japanese Knotweed is required by law on property development sites, with the Environmental Protection Act 1990 containing legal provisions classifying Japanese Knotweed as controlled waste. Moreover, negligent cultivation of the species falls into the remit of the Anti-social Crime and Policing Act 2014.

There are several schemes available to assist with the treatment and removal of Japanese Knotweed that come with insurance backed guarantees and are accepted by several lenders. However, it is advised that you seek specialist advice where an outbreak of Japanese knotweed is identified as the cost of remedy can differ based on the extent of growth and the specific removal process required.

How to identify Japanese Knotweed

Although this invasive plant has key recognisable characteristics, it is often mistaken for shrubbery, bamboo, or ornamental plants. If you suspect a property might have found Japanese Knotweed, we suggest contacting a specialist to correctly identify the plant.

The plant varies in its appearance throughout its growth cycle but can be identified in all stages.

In its fresh growth during early Spring, it produces reddish/purple shoots which develop into distinctive bright green leaves of a heart like shape, accompanied by small clusters of white flowers.

When the leaves and flowers start to die back the Japanese Knotweed leaves a characteristic zigzag shaped hollow cane which can grow over two metres tall with an average width of two centimetres.

Giant Hogsweed

The Giant Hogweed plant species was introduced from South-West Asia to British gardens in the early 1800’s. Often planted along rivers and ponds the species has become widespread and fairly well established across lowlands throughout the UK.

The main concern stemming from this invasive species is that the plant produces a phytotoxic sap when fully grown which can result in severe burns. Depending on the length of time the sap remains on your skin, this can cause continued problems for months after exposure.

While there is no obligation for landowners to remove or eradicate any Giant Hogweed, it falls within The Wildlife and Countryside Act 1981 and is subject to Anti-social Behaviour Orders.

Himalayan Balsam

Himalayan balsam is an invasive plant typically found along riverbanks and wastelands but is also a common invader of residential gardens. The plant can grow rapidly and spread at speed with each plant producing hundreds of seeds each year which project up to four meters upon release and disperse further through wind and water.

Environmentally the plant is detrimental to native plants and wildlife as it shades and crowds out other species. However, the chief concern of Himalayan Balsam lies within its root system.

The plant is an annual plant that dies back in the winter, when this happens the root system embedded into the ground also dies back. This causes destruction to the structure of riverbanks due to the instability to the embankment and encourages soil erosion which leads to siltation of rivers, increasing the chance of flooding.


While ivy isn’t typically considered as an invasive plant, it can be viewed as a nuisance and, in some cases, a danger to your property.  Large coverage of Ivy on a property also draws the risk of hiding defects in the property itself.

Although ivy can be aesthetically pleasing and even provides value for wildlife, the woody stemmed wall climber can greatly affect the structure of a property. English or common Ivy supports itself via aerial roots that penetrate through small cracks, which often leads to significant damage where defects already exist and can be particularly concerning around guttering.

However, unwanted ivy is fairly easy to treat and can be removed with certain weedkillers, or in the case of dead stems with no aerial roots, even be removed by hand.

Buying a home is one of the most expensive purchases you are likely to ever make, so don’t take the risk of buying one with hidden defects.

Book a home survey with SDL Surveying and we’ll help highlight if there are any issues with the property that may not be immediately obvious when viewing a property.

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