What are Japanese anemones? All to know about invasive plant

South Wales Argus

16 hours ago

From the more well-known Japanese Knotweed and Giant Hogweed to other lesser-known culprits, some can cause serious damage if left unchecked.
The worst invasive plants typically have UK laws in place to limit their spread into the wild.
However, this invasive plant might be one less know, so here is all to know about Japanese anemones.
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What are Japanese anemones?
As explained by the Royal Horticultural Society, Japanese anemones produce "saucer-shaped pink or white flowers on tall, slender, branched stems".
The plant is considered easy to grow and is best planted in autumn or spring.
They are herbaceous, which means they die back in winter and re-sprout in late spring.
When done correctly, they can be a good plant to grow.
Japanese anemones are available from plenty of garden centres, popular for their pretty pink or white open flowers with bright yellow centres.
Japanese anemones can be white or pink (Image: Getty Images) After flowering, they provide a good source of pollen and nectar for late-summer insects.
How to grow Japanese anemones
As shown by Gardener's World, Japanese anemones, if planted in summer, flower in September, "putting on a stunning show in late summer and early autumn".
It is suggested to plant Japanese anemones in moist but well-drained soil in light shade for the best results, as they will grow in most soil types, but struggle in wet winters.
Gardeners should then grow Japanese anemones in "moist but well-drained soil in light shade".
After planting, cut back after the Japanese anemones flower, or leave the seedheads for birds to eat in winter and then cut back after they have eaten them.
When caring for the plant, the RHS explains that when newly planted, Japanese anemones need watering regularly, for at least the first summer.
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Once established, they should only need watering in long dry spells or if growing in a dry site.
It is also recommended to mulch the plant, which is a layer of material placed on the soil around it to help it retain moisture and suppress weeds.
Are Japanese anemones invasive?
Despite the plant being a popular one to grow, experts warn that it can become invasive if left uncared for.
The plant spreads by underground runners and can "quickly become out of control, and is very difficult to eradicate".
They tend to be most invasive in loose, sandy soils, so it is recommended to consider growing them in a pot.
Gardener's World says: "When growing in the right conditions, Japanese anemones can spread easily and may become invasive and outgrow the space you intended for them.
"As well as self-seeding, they also send out rhizomes (spreading roots) that grow into new plants.
Double Japanese Anemone pic.twitter.com/lCmWDSA2ec — Darren Bird (@bird_darre5826) July 8, 2025
"To keep them under control, remove new shoots as they appear. Dividing and replanting established clumps can also help to control the spread of Japanese anemones."
How to remove Japanese anemones
If you are looking to remove the plant, as the Garden Doctor website says, it will take " a lot of effort and hard work".
Here is a guide to remove the plant:
Dig out the roots - Loosen the soil around the Japanese anemone, and gently lift the soil to unearth the roots without breaking them before using your hands to tease out the roots, ensuring you remove the entire network
- Loosen the soil around the Japanese anemone, and gently lift the soil to unearth the roots without breaking them before using your hands to tease out the roots, ensuring you remove the entire network Monitor the area - After removing the roots, continue to monitor the area over the coming weeks and months. New shoots may appear from any root fragments missed, so use your hands to pull them out from as deep as possible to get as much of the root as possible
- After removing the roots, continue to monitor the area over the coming weeks and months. New shoots may appear from any root fragments missed, so use your hands to pull them out from as deep as possible to get as much of the root as possible Mulch - Once most of the root system has been removed, cover the area with a thick layer of mulch, which works to suppress light and prevent any remaining Anemone roots from sprouting
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Experts warn to remain vigilant and patient, as the process of fully removing Japanese anemones can take up to two years.
It is also important to note that using herbicides will not be a quicker solution in the case of Japanese anemone.
The method of hand-pulling will be kinder to the garden and more effective long term.