GARDENING; Dare I plant a dahlia?

From the pink, frilly flowering cherries that spell between-the- wars suburbia to the valerian and verbascums that mark the laid-back Seventies, the plants we choose for our gardens date us as irrevocably as the width of our trousers. Helen Chappell investigates the rampant reversals of horticultural fashion

WHAT is it about plants and gardens that seems to cause amnesia? We dab our eyes at the sound of old Beatles songs and analyse every tuck and gusset in the history of modern fashion. Channel 4 broadcasts postmodernist tributes to Herman's Hermits and BBC2 celebrates the rise and fall of the hostess trolley in mid-Fifties domestic cookery. What do gardeners get to chart the history of the plants that have filled up their backyards over the 20th century? Not a thing. Garden snobs and old men in anoraks conspire to pretend that plants are not subject to the dictates of fashion like every other area of life. Only the occasional sepia snapshot reveals a lost world of regimented carpet bedding, dad with a Fair Isle jumper and pipe dwarfed by his hollyhocks, kids in cowboy hats astride the crazy paving.

Now that we are becoming less inhibited by false ideas of timeless good taste in gardens, it ought to be much easier to see where we have been and what things have looked like these last few decades. The end of a century, let alone a millenium, should inspire an outbreak of cultural stock-taking, and why should plants be left out in the cold? In many ways, what grows in our gardens is as evocative of the spirit of the age as jazz, mini skirts, bondage trousers, and Spam. Every trip to the garden centre, browse through glossy gardening magazine or glance round the potted- plant department of Marks and Spencer brings new clues to how our gardens look now or will look in the future. For those who believe that if you ignore history, you are doomed (nostalgically) to repeat it, there is no better time to explore the greenery of the past.

The RHS garden historian Dr Brent Elliott knows better than most how horticultural fashions, like all fashions, run around in circles. At the turn of the century (just as at the end of it) the vogue was for the cottage garden, full of "old-fashioned" flowers. "It was a reaction against the Victorian love of colourful, regimented bedding plants," says Dr Elliott. "Hybrids like pelargoniums, petunias and begonias were replaced by hollyhocks, sweet peas and herbs such as rocket."

If that sounds horribly familiar, he points out that conifers - beloved of the gloomy Victorians - were also "out". In their place came the first ornamental flowering trees and shrubs, many of them new varieties from Japan. It was a trend that gathered steam between the wars when every new suburban housing estate worthy of its mock-Tudor beams had its full quota of pink, frilly Japanese cherry trees. Walk down any Twenties or Thirties suburban street today and (cable TV contractors permitting) you will still find the same trees flowering their hearts out in pavement and front garden. Grown to giant maturity now, you will also find the monkey puzzle, creamy magnolia and acid yellow forsythia trees that were the last word in garden chic at the time. Bright colours cheered people up and staved off thoughts of the Depression and the dole queue. While the upper classes were being enchanted by the silver and pastel blooms of Vita Sackville-West's garden at Sissinghurst, the new suburbanites of Sunnyside Lane were happily planting their modest privet hedges and new-fangled hybrid tea roses.

The Second World War put an end to all this horticultural bliss, of course. With the exception of Russell lupins (introduced in 1938), fashions in the garden were banished in favour of ploughing everything up and growing vegetables for the war effort. Even public parks and country estates were expected to dig for victory.

The Fifties saw the first stirrings of the idea that modern life should be labour-saving and convenient. Abstract art began to influence garden design, introducing random shapes, asymmetrical lawns and kidney-shaped ponds. Garden magazines started to preach the gospel of low-maintenance and the use of ground-cover plants to smother weeds. Housewives were urged to use their "spare" time improving the home for hard-working hubbies. When not knocking up a perfect little dinner party for six, the Fifties wife was practising her new hobby of flower-arranging, Constance Spry guidebook at her elbow. The blooms she chose were as long-lasting and mess-free as possible, often the dahlias, carnations and chrysanthemums growing in her own garden.

The labour-saving garden reached its zenith of fashionability in the early Sixties with the publication of designer John Brookes's book, The Outdoor Room. Suddenly the garden was a place to lounge about in or entertain friends. While Beatlemania gripped the nation's youth, their parents attempted to be as "with it" as possible by installing pine panelling and picture windows in the house and a paved patio in the garden. As the garden was simply an extension of the house, it made sense to plant it up with non- demanding plants. "Back came the Victorian vogue for heathers and conifers," said Dr Elliott. Like sex, most people probably thought they had just invented it.

By the time the Sixties began to melt into the Seventies, the garden had become a much messier place. If not actually choked with cannabis plants, the backyard of the time was beginning to sprout older species plants rather than neat modern hybrids. Planting could be as wild and messy as people's hairstyles - it was the era of the tousled garden. The early ecology movement brought a vogue for the "natural" garden back once again. "The real ale and brown rice people went in for herbs, grasses and self-seeders like valerian and woolly verbascums," says the garden designer Jill Billington. "The rural nostalgic Laura Ashley bandwagon had knocked modern design on the head." Summer holidays in the newly fashionable Dordogne and Tuscany inspired a craze for clay pots on the terrace to match the Habitat Provencal fish kettle.

Prince Charles made great efforts throughout the Eighties to keep alight the flame of the environmentally friendly eco-garden. His earnest views encouraged the spread of organic and wildlife gardening, the banning of toxic chemicals and the vogue for wild-flower meadows and piles of rotting wood as homes for hedgehogs. Two other trends competed for the attention of the postmodern gardener, however. Eighties sophisticates with matt black Filofaxes went crazy for "architectural" plants where shape mattered more than colourful flowers. Hostas, gunneras, drumstick primroses, alliums, sea holly and rheums were all highly prized. Avant-garde designers like Myles Challis created complete replica jungles. "It was all part of the one-upmanship of the decade," says Jill Billington. "People competed to see how unusually shaped their plants could be."

The other major trend of the Eighties was the passion for (rediscovered) formality. Led by Sir Roy Strong and his shocking Italian garden at the V&A, garden-lovers tried to persuade every plant they could lay hands on to grow as a standard, including holly, bay, laurel, roses, hibiscus and fruit trees. Pergolas, gazebos, clipped box topiary and pleached lime allees made their first appearance since their revival in the Victorian era.

The fashion was fuelled by the new vogue for garden history and restoration and the rise of the garden designer. "Designers once worked only for the aristocrats and the wealthy," says Jill Billington, "but during the economic boom of the Eighties, people thought, if they could have someone to design the kitchen, why not the garden?"

At a time when he was running his successful costume-jewellery design business, Monty Don, now a garden writer, could not help noticing what was going on in the nation's back gardens. "People started seeing the garden as another fashion accessory," he recalls, "something to buy off the peg to impress your friends. Many people in that champagne and cocaine era had no interest in gardening at all, but they were quite happy to pay for someone else to do it for them."

This was the decade of the property boom, when yuppies bought and sold houses as a new form of speculation. The instant "country house come to town" garden was born. Whether attached to a des. res. or an innercity slum, this garden was all small, well-behaved trees (Robinia pseudoacacia "Frisia", Gleditsias, silver pears), topiary cones and rampant Russian vine smothering the eyesores and creating overnight "maturity".

Another recession brings us full circle into the Nineties. It's no surprise that plants have reacted against the past once again, with brightly coloured flowers making a comeback, just as in the depressed Thirties. "There's a distinct trend toward rich, strong jewel colours," reports Monty Don. "Soft pinks, greys and silvers are out and deep oranges, purples, dark blues and rich burgundy reds are replacing them." As for species, some of the most mocked and despised garden plants are poised for a comeback: dahlias, peonies, chrysanthemums and gladioli. The smartest lovers' bouquets now contain only blood- red "Nicole" or "Baccarole" (almost black) roses.

"It's a gesture against all that pastel good taste," says Monty Don. "The cottage-garden style has gone as far as it can and disappeared up its own backside."

The single most popular flower of the Nineties, however, has to be the sunflower. It appears everywhere now, from the front gardens of housing estates to shop-window displays, tea-towels, greetings cards and novelty loo-roll holders. The winner of the Perrier Comedy Award (male) has been presented with a bunch. Delia Smith put some on the cover of her best- selling Summer Collection cookery book. "It's the ultimate bold, happy flower," says florist Paula Pryke. "Orange and earth tones are in tune with our new awareness of the planet." Dr Elliot sees a connection with the sunflower as symbol of the fin du siecle decadence of the 1890s, along with the iris and the lily. It is also intriguing that sunflowers should be trendy at a time when interest in all things baroque (sunflowers were personal emblems of Charles I and Louis XIV) is on the rise.

The Nineties vogue for green flowers (green carnations a la Oscar Wilde, green orchids, bells of Ireland) and flowers from 17th-century Dutch still lifes (auriculas, ranunculus, parrot tulips) also seems to bear this idea out. "There's a what-the-hell attitude, a spirit of decadence starting to come over us," reckons Monty Don. "Plants are getting bolder and more quirky and exotic in response. I think it's a trend for the future." Paula Pryke agrees. In the future she sees a psychedelic jumble of acid green chrysanths, blood red dahlias, flame orange strelit-zias, metallic blue thistles and anthuriums with spots, blotches and stripes.

What all this says about the state of mind of gardeners as we reach the millennium is anybody's guess. And what sort of gardens will hold this dazzling array? "Gardens can only get more eccentric," predicts Monty Don. "I see them becoming a fanciful landscape for us to play and dream in." Perhaps there is a fashion message here for the next generation. With plants and gardens like these, who's going to need Ecstasy? !