Invasive plant species

• Japanese Knotweed
• Giant Hogweed
• High hedges
• What you should do
• Further information

Japanese Knotweed

Japanese Knotweed is a strong-growing, clump-forming perennial, with tall, dense annual stems.

Stem growth is renewed each year from the stout, deeply-penetrating rhizomes (creeping underground stems). It is widespread around Trafford appearing on waste ground, along watercourses and areas of previous tipping.

It is classed as an invasive species of plant, and is considered a particular problem as it can block footpaths and damage concrete, tarmac, flood defences and the stability of river banks.

Japanese Knotweed does not spread from seeds in the UK. It is spread when small pieces of the plant or rhizomes (underground root-like stems) are broken off. One piece of rhizome or plant the size of a fingernail can produce a new plant.

Pieces of plant or rhizome can be transported to a new location by:

• water - if the parent plant is close to a river or stream
• moving soil which contains them
• fly-tipping cut or pulled stems

Individual plants can cover several square metres of land, joined up below ground by an extensive rhizome network.

Legal implications

• It is not illegal to have Japanese Knotweed on your land
• You do not need to notify anyone about Japanese Knotweed on your land
• You are not obliged to remove or treat Japanese Knotweed, but you must not:
  • allow Japanese Knotweed to spread onto adjacent land - the owner of that land could take legal action against you;
  • plant or encourage the spread of Japanese Knotweed outside of your property - this can include moving contaminated soil from one place to another or incorrectly handling and transporting contaminated material and plant cutting.

Giant Hogweed

Giant Hogweed was introduced from the Caucasus to Victorian gardens in the 19th century. In the United Kingdom, Giant Hogweed has become extremely invasive in suitable habitats, such as river and stream banks, railway lines, disused waste land and other damp places.

Giant Hogweed is a tall, usually three to five metres, plant with several hundred small white flowers in large umbrella-like flower heads up to 500 millimetres across. Stems are green with dark-red or purple blotches and are hollow. Leaves are dark green and jagged in appearance and spiky are the ends.

Each flower head produces thousands of seeds, approximately 10 millimetres x 7 millimetres, that are easily dispersed by water, therefore the seeds can disperse rapidly along watercourses. The key identification features of the plant are:

• often grows up to three to five metres in height
• leaves expand up to 1.5 metres in width which have a jagged appearance with spiky ends
• large flower heads that are usually 50 centimetres wide, it is important to note that in the first few years of a giant hogweeds growth the main flowering shoot may not appear
• large seeds in clusters
• purple blotched stems with a fine hair like appearance
• hollow stems
• spread by seeds

Harmful effects

The stems, edges and undersides of the leaves have small hairs containing phototoxic sap. The slightest contact with human skin can cause painful blistering and severe skin irritation when exposed to sunlight. Blistering can take 24 to 48 hours to appear after exposure. The reaction can recur for six years or more.

If you do come into contact with giant hogweed cover the affected area of skin immediately from sunlight. Then wash the skin with cold water as soon as possible. If contact is with the eyes or blisters occur seek medical advice.

Legal implications

• It is not illegal to have Giant Hogweed on your land
• You do not need to notify anyone about Giant Hogweed on your land
• You are not obliged to remove or treat Giant Hogweed, but you must not plant or encourage the spread of Giant Hogweed outside of your property, this can include moving contaminated soil from one place to another or incorrectly handling and transporting contaminated material and plant cutting

High hedges

Tall hedges can be a nuisance, especially where neighbours can’t agree on a suitable height amicably. However, legislation now gives people whose gardens are overshadowed the opportunity to resolve the problem with the help of the Council.

What are high hedges?

The term ‘high hedges’ was subjective until it was defined by the Anti-Social Behaviour Act 2003: Part 8 in 2005. This is a summary of what constitutes a high hedge under the law:

• The hedge is more than 2m (approx 6½ft) tall (there is extra guidance for hedge heights on slopes) 
• A hedge is defined as a line of two or more trees or shrubs
• The hedge is formed wholly or predominantly of evergreens (these don’t lose their leaves in winter) or semi-evergreen ones (that stay green most of the year) 
• Bamboo and ivy are not included 
• Where a hedge is predominantly evergreen, the deciduous trees and shrubs within the hedge may be included in the work specified. However, the Council can exclude specific trees or require different work

Fact and fiction

There are some common misconceptions about the high hedges law, some of which are explained below.

What the law can do:

• It can override Tree Preservation Orders (TPO), although these will be considered when the complaint is evaluated 
• It may be decided that a hedge needs to be cut back in stages (e.g. over a period of three years to minimise the risk of killing the hedge)

What the law can’t do:

• It cannot require the removal of a hedge 
• Work that would result in the death of a hedge is not permitted 
• The Wildlife and Countryside Act 1981 makes it an offence to destroy any bird’s nest that is either in use or being built. The period given for cutting should take into account that, where birds are nesting in a hedge, work should not be carried out between March and August 
• Require homeowners to get permission to grow a hedge above 2m (6½ft) 
• When a hedge grows over 2m (6½ft), the local authority does not automatically take action, unless a justifiable complaint is made 
• The law can not be used as a preventative measure – the hedge must already be above 2m (approx 6½ft) tall and impairing reasonable enjoyment

What you should do

Japanese Knotweed

On your property, you should aim to control this plant and, to prevent it becoming a problem in your neighbourhood. If it does have a detrimental effect of a persistent or continuing nature on the quality of life of those in the locality new legislation could be used to enforce its control.

Control can be carried out by the homeowner and doesn't require a specialist company. Advice on controlling Knotweed can be found on our Knotweed guidance sheet. However, a specialist company will be skilled at control and can dispose of the plant waste.

Large stands of knotweed or knotweed on development sites require specialist treatment.

On no account should Japanese Knotweed be included with normal household waste or put out in green waste collection schemes.

Where problems with Japanese Knotweed occur in neighbouring gardens, we suggest that you speak or correspond directly with your neighbours (who may already be taking action to control this difficult weed).

Giant Hogweed

If you have Giant Hogweed on your property, you should seek to control this plant to prevent it becoming a problem in your neighbourhood.

Control can be carried out by the homeowner, and does not require a specialist company. However due to the dangerous nature of the plant we do not recommend this, a specialist company will be skilled at control and can dispose of the plant waste safely.

High hedges

If you have concerns regarding high hedges which you have been unable to resolve informally with your neighbour, you should contact the Council to begin the formal process of having the hedges evaluated.

Further information

Guidance on how to prevent harmful weeds and invasive plant species can be found on the GOV.UK website. The guidance also explains how you could risk a fine or prosecution if you do not deal with or dispose of invasive plants and harmful weeds properly.

If you would like to contact the Council to report issues or concerns regarding high hedges, you can write to:

Alternatively you can call us on 0161 912 3149