Darren Greatbatch, Specialist Advisory Manager, Amenity & Invasive Weeds, at Environment Controls.
Last reviewed on .
Invasive weeds in the UK: 4 dangerous plants that are not Japanese knotweed
Wondering what other plants in the UK are invasive that aren’t Japanese knotweed? There are many fast-spreading and potentially harmful species that are becoming more common – and just like knotweed they are affecting property, health, and the environment.
While Japanese knotweed is the most well-known, there are plenty of other invasive plants that are quietly spreading across the UK and should equally not be ignored. In this article experts warn of four other plants to watch out for if you want to avoid risk of an invasive infestation on property, land or construction sites.
Quick Answer: What Invasive Plants Should I Look Out for in the UK?
Four of the most concerning and lesser known invasive plants right now (other than knotweed) include:
- Gaultheria shallon (Shallon / Salal)
- Ailanthus altissima (Tree of Heaven)
- Ambrosia (Ragweed)
- Datura stramonium (Devil’s Trumpet)
These plants can cause environmental damage, property issues, or health risks.
1. What is Gaultheria shallon and why is it a problem?
Gaultheria shallon is an invasive evergreen shrub spreading across parts of the UK.
Why it’s a concern:
- Forms dense, impenetrable thickets
- Prevents native plants from growing
- Stops natural woodland regeneration
It is particularly problematic in the South of England.
In Scotland, allowing it to spread in the wild can breach the Wildlife and Countryside Act 1981.
2. Can Tree of Heaven damage property?
Yes – Ailanthus altissima is a fast-growing invasive tree that can cause structural issues.
Key risks:
- Roots can damage foundations, drains, and sewers
- Spreads quickly in urban areas
- Produces a strong, unpleasant smell
This plant is increasingly found during property surveys and development site inspections.
3. Is ragweed dangerous in the UK?
Ambrosia (ragweed) is one of the most harmful plants for allergy sufferers.
Why ragweed is a problem:
- Produces huge amounts of pollen
- Causes severe hay fever symptoms
- Can trigger or worsen asthma
It extends allergy season into late summer and autumn.
4. Is Devil’s Trumpet poisonous?
Yes – Datura stramonium is highly toxic.
Risks include:
- Severe poisoning if ingested
- Hallucinations and confusion
- Dangerous for humans and animals
This plant should never be handled without proper protective equipment.
What should I do if I find an invasive plant?
Do not attempt to remove it yourself.
Instead:
- Avoid disturbing the plant or soil
- Take photos for identification
- Contact a professional invasive species specialists – we can help
Incorrect removal can cause rapid spread and higher costs.
Are invasive plants a legal issue in the UK?
Yes – certain invasive species are regulated under the Wildlife and Countryside Act 1981.
You could be liable if:
- You allow invasive plants to spread into the wild
- You mishandle contaminated soil
- Your actions impact neighbouring land
Why are invasive weeds increasing in the UK?
Invasive plants are becoming more common due to:
- Climate change and warmer conditions
- Movement of soil and materials
- Lack of early identification and management
This makes early detection more important than ever.
Expert Insight
Jennifer Holmes of Environment Controls Ltd explains: “Many people associate plant risks with well-known species like Giant hogweed, hemlock and Himalayan balsam but there are a growing number of invasive and harmful plants that can affect both people and the environment. Correct identification is essential before taking any action – our free online ID tool is the fastest way to find out if you have a problem plant to deal with. For construction, groundworks and development it’s crucial to have invasive plants identified before works commence as any ground disturbance is a biosecurity hazard. Works should halt whilst experts carry out a survey to report the extent of the infestation and advise on options for removal.”
Can I remove invasive weeds myself?
In most cases, no.
DIY removal can:
- Spread the plant further
- Disturb root systems
- Lead to legal and environmental issues
Professional treatment (often herbicide-based or controlled removal) is usually required.
Final Takeaway
If you’re searching for:
- “plants like Japanese knotweed”
- “dangerous plants UK”
- “invasive weeds UK identification”
The key message is simple:
Japanese knotweed isn’t the only invasive threat.
Plants like Gaultheria shallon, Devils Trumpet, Ragweed and tree of Heaven are becoming more common and can cause serious issues if left unmanaged.
If you have a question about a suspect plant and would like us to correctly identify it for you – or if you know you’ve got a problem plant and would like to speak to us about removing it please contact the team
People Also Ask
- What invasive plants should I worry about in the UK? Japanese knotweed is the most well-known, but others like ragweed, Tree of Heaven, and Devil’s Trumpet are also increasing.
- Can invasive plants damage property? Yes – species like Tree of Heaven can damage structures through aggressive root systems.
- Are invasive plants harmful to health? Some are – ragweed causes severe allergies, and Devil’s Trumpet is highly toxic.
- Is it illegal to have invasive plants? It’s not illegal to have them on your land, but it can be illegal to allow them to spread.