Gardens and green spaces shape the UK’s natural beauty, offering a haven for plants and wildlife. However, not all plants contribute positively to the delicate balance of our native ecosystems. Some non-native species, introduced from other parts of the world, have taken root a little too successfully, spreading aggressively and outcompeting native plants. While many non-native plants pose no threat, a handful have become invasive, disrupting ecosystems and even causing structural damage. There are over 35 plants that are deemed to be invasive non-native plants in the UK as they spread rapidly and threaten ecosystems, habitats or native species.
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What is an invasive plant?
More troublesome than an out-of-control weed, a plant is considered invasive when it begins to threaten existing habitats and ecosystems either by spreading rapidly, becoming difficult to control or competing with non-invasive plants for valuable resources such as light, nutrients and water.
It can take years for some plants to become a problem. Gardeners often find themselves with invasive non-native plants in their gardens as they were planted decades before.
As well as causing damage to plant communities, invasive plants have the potential to damage hard surfaces such as paving or drains and in some worst cases, large structures and buildings. Particularly if there is pre-existing damage or cracks for the plants to grow into.
Below are 10 invasive plants listed on the Wildlife and Countryside Act 1981, along with advice on how to manage them if they’ve already taken hold.
Jump to
- UK regulations on invasive non-native plants
- What to do if you find an invasive species in your garden
10 invasive non-native plants
Fallopia japonica (Japanese Knotweed)
Notorious for its invasiveness, Japanese Knotweed is a particularly aggressive plant which requires specialist treatment. The Environment Agency must be informed whether you decide to treat the plant at the growth site or remove and dispose of the plant at an authorised facility. Gov.uk has detailed information and guidance for identifying, removing and disposing of Japanese Knotweed.
Gunnera tinctoria (Giant Rhubarb)
Once admired for its large, umbrella-like leaves, giant rhubarb plants have been banned from sale since 2023 because of its impact on native biodiversity, you can read more about the ban here. It spreads quickly through seed dispersal – birds love to eat these – and its root system, and the sheer size of the plant blocks sunlight and nutrients to native species. To stop it spreading in your garden and beyond, cut the flower heads in summer and burn them on site. If you’d rather remove it completely, let the plant die back in winter and then dig down to at least a metre to remove the stump and its rhizome root system. In some cases a herbicidal treatment may be necessary.
Heracleum mantegazzianum (Giant Hogweed)
Although beloved by pollinators, this enormous umbellifer escaped into the wild in 1828 and has since spread throughout much of the UK. If you need to remove a plant from your garden, the best method is to dig out the whole plant before it flowers and sets seed. Giant Hogweed is classed as ‘controlled waste’, and you’ll have to inform the Environment Agency and dispose of the plant at a registered site. If you do need to remove a plant from your garden, wear protective clothing as sap from Giant Hogweed can cause burns when exposed to sunlight.
Crocosmia x crocosmiiflora (Montbretia)
This colourful perennial is a common garden plant in the UK, and its arching stems of deep orange bell-like flowers are easily recognisable. However, its spread into the countryside is a cause for concern, earning it a place on schedule 9 of the Wildlife and Countryside Act. Spreading vigorously through a network of rhizomes, the plant is now endemic in many of our native habitats and it’s endangering local ecosystems. To get rid of the plant from your garden, you’ll need to dig it up, but if it’s a well-established plant, you may need a more industrious method than the trusty garden spade. Mechanical diggers or herbicides may be the only solution if the spread is extensive.
Rhododendron ponticum (Rhododendron)
There have been incredible efforts to eradicate Rhododendron from the British Isles, particularly in Scotland where the evergreen shrub is damaging the country’s rare native rainforests. Although attractive and once a prized ornamental garden plant, Rhododendron has an aggressive growth habit, seeds prolifically through wind dispersal, and forms large, dense bushes which steal sunlight and nutrients from native habitats. Although you can manually remove Rhododendron, control methods vary depending on the size of the plant, and regrowth from seeds is common as they can remain viable for up to 3 years.
Cotoneaster horizontalis (Cotoneaster)
This deciduous shrub, formed of long horizontal stems of herringbone-like foliage, is another common garden plant which has become invasive in the UK. According to the Wildlife Trust, it’s taken over large sections of limestone grassland and has outcompeted many of our native species. Spread by bird droppings, the plant establishes itself quickly and roots dig-in deep. There are actually five different Cotoneaster species on the offenders list and if you have any of them growing in your garden, you should make sure to dispose of any cuttings responsibly. Contact your local authority to check how to do this without risk of a fine.
Carpobrotus edulis (Hottentot fig)
Native to South America, Carpobrotus edulis was introduced to the UK as an ornamental trailing shrub in the 17th century but has since been classed as invasive. Succulent-like in appearance, the plant forms dense mats that can change the characteristics of the soil and threaten the survival of other plants. It’s still widely sold as hardy ground cover, but to save yourself the risk of a fine it might be best to avoid planting this fleshy-leaved creeper in your garden.
Ludwigia grandiflora (Water Primrose)
Invasive aquatic plants are particularly difficult to control which is why the worst offenders have now been banned from sale. The Water Primrose is one of these, and it’s terrorising our waterways. It forms huge mats on the water’s surface and although the yellow flowers are pretty, the floating vegetation steals sunlight and oxygen from other native plants and aquatic life. It can reproduce quickly from small fragments, so take extra care when removing this plant from a pond or stream. Unfortunately, because of the risk it poses to our native ecosystems, either chemical or mechanical methods of removal are preferred, but for small patches of growth, digging out and composting the whole plant away from water sources may be enough. You can find detailed information at nonnativespecies.org.
Impatiens gladulifera (Himalayan balsam)
Commonly spotted along waterways, this tall annual with scented flowers in shades of pink and purple achieves its vigorous spread through seed dispersal, growing into a dense plant which outcompetes native species for vital resources. Himalayan balsam is the third plant on our list which is regarded as ‘controlled waste’. This means the Environment Agency needs to be informed of any removal, and it can only be disposed of at registered waste or landfill sites. The best way to manage Himalayan balsam if you already have it growing in your garden is to prevent the plants from flowering and setting seed.
Rosa rugosa (Japanese Rose)
A popular hedging plant, Rosa rugosa is tough and easy to grow with attractive pink, fragrant blooms in the summer and bright red rosehips in autumn. It spreads quickly from seed and resilient suckers, and forms dense thickets that can shade out and smother native plants, dramatically altering delicate habitats. Although not banned from sale, this Japanese Rose poses a high-risk of a fine because gardeners like to grow it along boundary walls where it could easily escape. If you already have an out-of-control plant growing in your garden, the plant and its entire root system will need to be dug-up and the excavated plant will need to be burned or buried at least 2 metres underground to prevent re-growth.
UK regulations on invasive non-native plants
Regulations exist in the UK to prevent further sales or planting of non-native invasive plants. Rules vary from country to country.
In England and Wales, many invasive non-native plants are listed under Schedule 9 of the Wildlife and Countryside Act 1981, making it illegal to plant or encourage their growth in the wild.
The Wildlife and Natural Environment Act (Scotland) 2011 makes it illegal to plant any non-native plant in the wild in Scotland.
If a listed plant is already growing on your land, Defra does not consider it to be intentionally kept or cultivated and you’re not committing an offence. This includes plants in private gardens, parks and estates open to the public. You do not have to remove listed plants growing wild on your land. However, you must not intentionally grow, cultivate, sell or allow wild listed plants to reproduce.
If any of these invasive plants appear or are already established in your garden, it’s your responsibility to prevent them from spreading and causing harm to surrounding landscapes, or you might be fined.
Read more about Defra's advice on non-native plants
What to do if you find an invasive species in your garden
While discovering an invasive species in your garden can be daunting, the first step is accurate identification. Before taking action, it’s crucial to ensure you're targeting the right plant with the right method – misidentification could lead to ineffective control or accidental harm to beneficial species.
Once you have confirmed the identity of your plant, you can choose the most suitable approach for removal:
• Responsible management
Keep a close eye on invasive species to prevent their spread. Regular monitoring and early intervention can stop them from taking hold in new areas.
• Manual removal
Carefully extract the plant using organic or chemical methods. Some species may require repeated treatments or disposal in a controlled manner to prevent regrowth.
• Professional intervention
For aggressive or deeply established species, expert assistance may be the safest option. Specialist removal services can ensure the plant is eradicated effectively and disposed of at registered landfill or waste sites.
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Although it is enshrined in law, there does not seem to be any reported enforcement action undertaken by Natural England or the Environment Agency in the last year for this specific offence. However, it is worth being careful if you spot any of these plants to make sure they don't spread to neighbours' gardens or the countryside, or cause damage to or lower the value of your home. For serious offences, you could be facing up to two years imprisonment, or an unlimited fine. For lesser offences, up to a year's imprisonment and a fine of up to £40,000 (or both).