Invasive plant species
You'll find some information below on how to recognise these species for yourself in your garden or on your land, and what to do if you find them.
Together we can all take steps in helping reduce this threat and slowing the advance of these species.
American skunk cabbage
How to recognise: The plant has huge leathery leaves between 40cm – 1.5m, and bright yellow 'flowers' up to 45cm, which resemble those of Lords and Ladies. The yellow 'flowers' emerge first around April time, followed by the leaves.
What to do: Dig out the plants, including new seedlings and rhizomes. Be thorough, as any remaining rhizome fragments can regenerate into new plants. If this isn’t possible, leaves can be treated with herbicides between June and October, but if they are near a watercourse, you will need approval from the Environment Agency. Dispose of plant material by burning, secure composting or drying out on land which will not be flooded and is away from watercourses.
Himalayan balsam
How to recognise: This plant can grow up to 3m high, with reddish translucent stems, dark green lance-shaped leaves with jagged edges, and bright pink to purple flowers between June and October, which become explosive seed pods.
What to do: Grasp the plant at its base and pull it out of the ground, ensuring you remove the root system completely. Pile the uprooted plants in an area off the ground to prevent them from rerooting. Revisit the area after a few weeks to check for any signs of regrowth and remove any new plants immediately.
Japanese knotweed
How to recognise: It has bamboo-like stems with purple speckles, large, heart-shaped green leaves, white flowers in late summer, and can reach up to 3 meters in height.
What to do: The most effective and recommended approach is to hire a professional Japanese knotweed specialist. Professional treatment often involves herbicide application, which may take 3-5 years. Professional excavation and removal is also an option, and aims for complete removal of the plant and its extensive root system. Regardless of the treatment method chosen, ongoing monitoring is crucial to ensure the knotweed doesn't return.
Parrot’s feather
How to recognise: This plant has distinctive blue-green, feathery leaves arranged in whorls along the stem. It typically grows in water or very moist conditions.
What to do: If you have a small infestation, you can manually pull out the plant. It’s crucial to remove entire plants to prevent fragmentation, which can lead to further spread. This should be done regularly (every 6-9 weeks) to weaken the plant. For larger infestations, consider using glyphosate-based herbicides specifically designed for aquatic plants. This method should be done carefully and ideally under guidance from professionals to minimize harm to native species. The plants must be disposed of as controlled waste.
Ragwort
How to recognise: This biennial plant has tall stems, clusters of daisy-like yellow flowers, and deeply lobed leaves. Growing to around 90cm high, it flowers from July to October.
What to do: Ragwort is a native plant and is beneficial to many insects, however, you have a legal obligation to control ragwort if it poses a risk to livestock or spreads to agricultural land. Failure to manage ragwort can result in fines or control orders from DEFRA. It can be removed by hand pulling, ensuring that you remove the entire root system, as it can regenerate from fragments. Always wear gloves to avoid skin irritation. Dead plants remain toxic and should be burned or disposed of in sealed bags to prevent seed spread.