GARDENING / It crept out of the border: Beware the space invaders. Plants that start life as lovely little climbers can fast turn into garden thugs. Helen Chappell reports

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IT WAS like a scene from a Fifties science fiction movie - the panic, the terror, the hopeless struggle against a ruthless alien invader. Watching our next-door neighbours clawing at Russian vine with their bare hands the other week racked us with guilt.

We had introduced this menace into their lives, after all. I distinctly remember my loved one picking it up at the garden centre and planting it against the trellis with the cheery words, 'this ought to give us a bit of privacy'. How were we to know that all the gardening books warned about its 'vigorous and invasive growth'? We wanted a nice little climber that would grow quickly and block a gap in the fence. We have ended up with a writhing mass of tendrils, thrusting indoors under our conservatory roof and slithering over the fence to strangle the people and plants next door.

We think we have got it under control now, after a weekend of energetic slashing, yanking and unwinding. But once you have made the mistake of planting something insanely rampant you can never feel secure. An overlooked shoot or root is always twitching away somewhere, underground, plotting its revenge. The only answer is to avoid the problem in the first place.

Before the next visit to the garden centre, we are determined to do our homework. No more falling for labels with pretty pictures. No more asking the advice of casual staff. I have been studying the projected height, width and spread of everything from a snowdrop to a silver birch before planting for next spring. What's more, I have been consulting the experts to discover their 'hit lists' of avoidable space invaders.

David Barker, vice president of the Hardy Plant Society, would place the legendary Japanese knotweed at the top of his list. Fallopia japonica is a plant which has escaped, triffid-like, from the garden to colonise waste ground and railway embankments all over the country. It creates shade so dense that nothing else can survive and it is almost impossible to destroy. 'I've had real trouble with the Caucasian comfrey, Symphytum caucasicum, too,' reports Mr Barker. 'I bought one to plant in a shady corner under my old apple trees. The spikes of blue tubular bells are very attractive. But I soon found that it spreads like mad and smothers everything it can reach. I tried to dig it up but, five years later, bits of it are still trying to take over.'

He says its partner in crime is the variegated deadnettle, Lamium galeobdolon 'Variegatum'. This innocent-looking plant had seemed just the thing to cheer up a patch of dry shade. 'Then it started sending out long runners everywhere with tiny plantlets which instantly took root. I keep jumping on each new shoot, but this chap still comes up.'

Then there are notorious garden thugs like Vinca major, Clematis montana and the ruthless self-seeders Geranium x oxonianum 'Claridge Druce' and Alchemilla mollis. 'Garden centres should warn people more clearly about some of these plants,' says Mr Barker. 'If the label says 'vigorous spreading habit' or 'good ground cover', watch out. They're like estate agents' descriptions. You always have to read between the lines.'

Plant labels and nurserymen who are economical with the truth are also the pet hate of landscape designer Marianne Bailey. 'Garden designers and other experts can make mistakes with their planting too,' she says. 'Especially with trees and shrubs. I have planted the white poplar in a beautiful formal scheme, only to have my clients on the phone a couple of years later complaining about a plague of root suckers coming up all over the lawn.' Shrubs like the sea buckthorn, Hippophae rhamnoides (a demon on sandy soils and public enemy number one on the Channel Islands) and Rubus tricolor are also high on her horticultural hit list. Clients requesting self-clinging climbers like the Irish ivy or Virginia creeper are now given grave warnings about their thuggish habits and tendency to block up gutters and boiler outlets when grown against the house.

'It can be difficult to argue with people who have fallen in love with a plant they've seen growing in a friend's garden or the grounds of a stately home,' says Ms Bailey. 'I try to make them realise that they don't have the same amount of space for it to rampage about in.'

Indeed, a plant which seems to us to be bent on global domination may simply be doing its own thing in overcramped conditions. 'There are no rogue plants, only plants in the wrong place,' says Brian Davis, author of The Good Plant Guide. 'Take the bush, Kolkwitzia amabilis. People are always trying to squash it into a small place in the border, but it actually grows up to 15 feet high.' Novice gardeners can also be taken in by the word, 'dwarf'. Botanists use it simply as a comparative term meaning smaller than the original parent plant (which might be enormous). 'Another problem is that most garden centres only quote plant measurements after four or five years,' says Mr Davis, 'rather than the ultimate size.' They think customers only want to keep a plant for a few years, but that isn't true.'

But there are still some rampant plants which he would include in a hit list to avoid at all costs. Few average gardens could contain the ambitions of Rosa filipes 'Kiftsgate,' a climber which is often recommended to cover old tree stumps and other eyesores. 'That's an animal,' says Mr Davis. 'It can grow 20 or 30ft in one year,' he points out. 'It may look beautiful but it has thorns like fish hooks. It comes from the Himalayas where it romps away over hundreds of feet.'

On a smaller scale, the summer jasmine will grown 25ft in both directions given half the chance. Grow it romantically around the front door of your house and you may find you can't get out. And too few people realise that the ubiquitous hedging Leyland cypress is a forest tree which will eventually grow 150ft tall.

According to Mr Davis, there really is no substitute for doing your research before buying the plant of your dreams. 'But don't be misled by Latin names like repens and pyramidalis ,' he warns. 'Often they describe plants that neither creep along the ground nor grow up pencil-slim. You could end up with something five feet tall or 20ft wide.' Cold hard figures are the things to search for - rather than dredging up our rusty O level Latin and struggling to make sense of names. To avoid a back garden invasion of alien tendrils, suckers, branches and seedlings, it seems, that there is only one Latin phrase which we can rely on and that's Caveat emptor - let the buyer beware.

A realistic guide to the height and spread of garden plants (including trees and shrubs) is provided in the 'RHS Gardeners' Encyclopedia of Plants and Flowers' (Dorling Kindersley, pounds 29.95).

(Photograph omitted)

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