Japanese knotweed

Japanese Knotweed is an invasive non-native plant (INNP) that has become a serious problem in some areas of the UK.

It can -

  • spread quickly
  • takes over other plants
  • cause damage to property.

It commonly spreads quickly by -

  • rhizomes (roots)
  • crown (base of the stem)
  • stem segments

if damaged or disturbed for example during -

  • garden clearance
  • construction work
  • garden waste.

To help understand whether you may have found Japanese Knotweed, or other forms of non-native invasive species access the Non-Native Species Secretariat website.

It causes problems because it -

  • can force its way through concrete or brick, so can damage buildings or roads
  • grows in thick clusters, which means native plants can’t grow
  • is very difficult to get rid of
  • can result in a reduction in land values and affect the ability to get a mortgage

On your property

If you find Japanese Knotweed growing on your land, you should treat the plant as early as possible to stop it from spreading and becoming a problem.

Tell your neighbours if you believe you have Japanese Knotweed on your land, so they can see whether it is present in their gardens.

Early identification and treatment will stop the plants from further spreading.

It usually takes at least three to four seasons to remove Japanese Knotweed using the appropriate weed killer. If using chemical treatments please ensure these are used safely. Follow manufacturer's instructions and wear appropriate PPE at all times.

If you are considering using any form of chemical agent and your land is next to or near any watercourse, contact the Environment Agency prior to any treatment taking place by calling 03708 506 506. Avoid damage to non-target plants by spraying during still dry conditions, without rain for 6 hours.

If you intend to spray any chemicals on any land which is not your own, you will likely need to be an approved contractor with a National Proficiency Tests Council Certificate of Competence if spraying on land which is not your own.

If you find this is ineffective, we recommend you contact professional contractors who have access to more powerful chemicals that may reduce this period by half.

When dealing with Japanese Knotweed on your property you must not -

  • dispose of any part of the plant in your brown wheelie bin, black wheelie bin or compost bin
  • spread soil contaminated with Japanese Knotweed as this could affect a greater area
  • take it to your local household waste and recycling site
  • dump or fly-tip cuttings

Instead you must stop Japanese Knotweed spreading from your land and you could face legal action and costs if you allow it to spread onto someone else’s property.

On your neighbour’s property

If you're concerned that Japanese Knotweed may be on your neighbour's land or private owned land and it may spread onto your property, we recommend you first try to speak to them and make them aware of what you have found, as they might not realise there’s an issue.

If your neighbouring property is owned by us, contact us by calling 01482 300 300 and request to speak to our Housing or Property Team.

If this doesn’t work, we would recommend you contact the Citizens Advice Bureau or seek independent legal advice.

If you feel your property is being damaged we would also recommend you speak to your home insurance company for help and advice. 

Further information can be found here.

On land around a railway

If you find Japanese Knotweed next to a railway line, embankment or station, contact Network Rail and ask them to treat the problem and confirm.

In a park, public land, open space or other Council land

To report Japanese Knotweed in any -

  • park
  • public land
  • open space
  • other form of Council land

Contact us by telephone - 01482 300 300.

Giant hogweed

Giant hogweed is an invasive non-native plant (INNP) advice should be followed, as above, in regard to its removal and treatment.

You should follow the same advice as to the removal of Japanese Knotweed, which will vary on whether this is on private land, Council land, public open spaces or railway land.

It should be advised that sap from this plant contains a chemical which, in the presence of sunlight, can cause a potentially dangerous skin reaction with those who come into contact with it. Symptoms may include -

  • burning
  • itching
  • blistering

Blistering can take 24 to 48 hours to appear after exposure, and dense pigmentation is visible after three to five days. Any lesions caused from contact may be slow to heal and could result in consequent scarring, which may persist for a number of years. Any reaction to giant hogweed can be especially acute in children.

If persons have come into contact with giant hogweed, it is recommended they cover the affected area of skin immediately from sunlight, and wash the affected skin with cold water as soon as possible. If contact is with the eyes or blisters occur, seek medical advice immediately.

For further advice in regard to Giant Hogweed, please visit the Royal Horticultural Society (RHS) Gardening / Giant hogweed advice page.