Chelsea Flower Show warns of alien plant invasion


Visitors to Britain's most famous gardening event, the Chelsea Flower Show, will be confronted with an unusual display this year: a garden they will be warned not to plant.

Visitors to Britain's most famous gardening event, the Chelsea Flower Show, will be confronted with an unusual display this year: a garden they will be warned not to plant.

The event's 157,000 visitors will be told about the increasing dangers posed by invasive species - the often alien flowers, ornamental plants and pond weeds that are devastating the countryside.

The unique display, which will take pride of place at the show's Great Pavilion when it opens on 25 May, will alarm many gardeners because it features 10 flowers, aquatic plants and "architectural" species being promoted by Britain's booming garden centres.

Most of these plants have never been so publicly branded as dangerous - such as gunnera, a South American plant known as "giant rhubarb" which is infesting marshy areas of Ireland, and montbretia, which is spreading out of control along hedgerows and streams.

The display, designed by ecologists and botanists from English Nature and the Environment Agency, will feature several of the plants now choking ponds and streams, such as parrot's feather and floating pennywort.

These plants have already begun overpowering native species in south-west England, said Trevor Renals, an Environment Agency ecologist in Cornwall, and are threatening to spread elsewhere in England and Wales.

Mr Renals said the chief problem was the desire for "instant gardens" being promoted by makeover programmes and garden centres, featuring quick-growing plants that are often invasive species which run out of control.

"There seems to be a climate where people want instant gardens," he said. "But people should learn to tolerate bare patches for a year or two rather than going for a quick fix with these invasive species, and then having to spend their time pulling them up when they spread too far."

The agency, English Nature and councillors formed the Cornwall Knotweed Forum, an umbrella group originally set up to combat knotweed - an invasive ornamental plant which came to the UK in the mid-19th century from Japan. Knotweed is now one of the most hated plants in Britain because of its tenacity and speed of growth.

The forum installed a small knotweed display at last year's Chelsea Flower Show, which won a gold medal from the Royal Horticultural Society. The group has now branched out to campaign for tighter controls on all invasive plants.

This year's exhibit is based on a Cornish field. Drawing on a theme of celebration of the RHS's bicentennial year, the display is split in two.

One half features native Cornish plants typical of 1804, but across a hedge is a modern Cornish field which has been over-run by invasive species, brought there by the illegal dumping of garden waste - one of the most effective ways of spreading garden plants through the countryside.


Dead nettle: Lamium galeobdolon

Origins: North Africa and Eurasia

Appearance: Short, upright stems of silver-streaked foliage with clusters of small, hooded yellow flowers from late spring to midsummer.

The problem: Also known as yellow archangel and Hermann's pride, it will spread rapidly, especially in woods, crowding out other flowers.

Winter heliotrope: Petasites fragrans

Origins: Mediterranean North Africa

Appearance: Thick, heart-shaped leaves, with pinkish-white flowers between December and March. The problem: Also known as sweet-scented coltsfoot, it will grow thickly in woodland and road edges, smothering native species.

Montbretia: Crocosmia x crocosmiiflora

Origins: South Africa

Appearance: A bulbous plant which dies down in the autumn. Bright green and spear-shaped leaves appear in spring together with long spikes of tubular orange flowers.

The problem: Competes fiercely with indigenous plants in hedgerows and along streams.

Three-cornered leek or garlic: Allium triquetrum

Origins: Western Mediterranean

Appearance: A bulbous plant with drooping white flowers from late winter to June. Its stems are sharply triangular and give off a strong smell of garlic when crushed.

The problem: Looks like a white bluebell, but its quick growth means it will over-run entire areas.

Gunnera: Gunnera tinctoria

Origins: South America

Appearance: An enormous plant with leaves that can grow to up to 4ft wide. Produces large spikes of reddish-green flowers during the summer.

The problem: Known as Chilean or giant rhubarb, gunnera can swamp damp or boggy areas.

Annabel Fallon

  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
iJobs Job Widget
iJobs General

Recruitment Genius: Project Implementation Executive

£18000 - £23000 per annum: Recruitment Genius: They work with major vehicle ma...

Recruitment Genius: Chiropractic Assistant

£16500 per annum: Recruitment Genius: A Chiropractic Assistant is needed in a ...

Recruitment Genius: Digital Account Executive - Midlands

£18000 - £26000 per annum: Recruitment Genius: They work with major vehicle ma...

Recruitment Genius: Web Developer

£28000 - £30000 per annum: Recruitment Genius: This company provides coaching ...

Day In a Page

NHS struggling to monitor the safety and efficacy of its services outsourced to private providers

Who's monitoring the outsourced NHS services?

A report finds that private firms are not being properly assessed for their quality of care
Zac Goldsmith: 'I'll trigger a by-election over Heathrow'

Zac Goldsmith: 'I'll trigger a by-election over Heathrow'

The Tory MP said he did not want to stand again unless his party's manifesto ruled out a third runway. But he's doing so. Watch this space
How do Greek voters feel about Syriza's backtracking on its anti-austerity pledge?

How do Greeks feel about Syriza?

Five voters from different backgrounds tell us what they expect from Syriza's charismatic leader Alexis Tsipras
From Iraq to Libya and Syria: The wars that come back to haunt us

The wars that come back to haunt us

David Cameron should not escape blame for his role in conflicts that are still raging, argues Patrick Cockburn
Sam Baker and Lauren Laverne: Too busy to surf? Head to The Pool

Too busy to surf? Head to The Pool

A new website is trying to declutter the internet to help busy women. Holly Williams meets the founders
Heston Blumenthal to cook up a spice odyssey for British astronaut manning the International Space Station

UK's Major Tum to blast off on a spice odyssey

Nothing but the best for British astronaut as chef Heston Blumenthal cooks up his rations
John Harrison's 'longitude' clock sets new record - 300 years on

‘Longitude’ clock sets new record - 300 years on

Greenwich horologists celebrate as it keeps to within a second of real time over a 100-day test
Fears in the US of being outgunned in the vital propaganda wars by Russia, China - and even Isis - have prompted a rethink on overseas broadcasters

Let the propaganda wars begin - again

'Accurate, objective, comprehensive': that was Voice of America's creed, but now its masters want it to promote US policy, reports Rupert Cornwell
Why Japan's incredible long-distance runners will never win the London Marathon

Japan's incredible long-distance runners

Every year, Japanese long-distance runners post some of the world's fastest times – yet, come next weekend, not a single elite competitor from the country will be at the London Marathon
Why does Tom Drury remain the greatest writer you've never heard of?

Tom Drury: The quiet American

His debut was considered one of the finest novels of the past 50 years, and he is every bit the equal of his contemporaries, Jonathan Franzen, Dave Eggers and David Foster Wallace
You should judge a person by how they peel a potato

You should judge a person by how they peel a potato

Dave Hax's domestic tips are reminiscent of George Orwell's tea routine. The world might need revolution, but we like to sweat the small stuff, says DJ Taylor
Beige is back: The drab car colours of the 1970s are proving popular again

Beige to the future

Flares and flounce are back on catwalks but a revival in ’70s car paintjobs was a stack-heeled step too far – until now
Bill Granger recipes: Our chef's dishes highlight the delicate essence of fresh cheeses

Bill Granger cooks with fresh cheeses

More delicate on the palate, milder, fresh cheeses can also be kinder to the waistline
Aston Villa vs Liverpool: 'This FA Cup run has been wonderful,' says veteran Shay Given

Shay Given: 'This FA Cup run has been wonderful'

The Villa keeper has been overlooked for a long time and has unhappy memories of the national stadium – but he is savouring his chance to play at Wembley
Timeless drama of Championship race in league of its own - Michael Calvin

Michael Calvin's Last Word

Timeless drama of Championship race in league of its own