This happened soon after what Smit (who trained and worked briefly as an archaeologist) calls his epiphany:

one fine day in Paris, with hit songs he had written in the charts and money to burn, he was being driven along the Champs Elysees in a customised limo when he suddenly started to cry, and cry, at the emptiness he felt inside.

"Whenever I went walking in nature at that time, it didn't feel real, " he explained in London last week, where he was due to give a talk on the future of The Eden Project, another of his very big ideas that has come to fruition in Cornwall.

"Then in Phoenix, Arizona, I saw they had built these amazing big biomes for scientific experiments on plants for outer space. I read in Scientific American about plants whose roots actively avoided each other, even behind glass, and I thought, what's that all about? I began to realise that plants were not passive but very active, and there must be a reason."

Smit decided to trust his instincts and "dare to be the person I wished I was when young: one who sleeps well and is good, " he said, mocking himself in a likeable manner not often apparent in messianic types. So Tim stopped busking it and, with John (Nelson), bought Heligan.

The rest is recent history and Heligan is rightly one of the top visitor attractions anywhere.

With The Eden Project, too, Smit's passion for his subject and upbeat approach to life . . . "I won't have anyone negative near me, negativity spreads and kills things" . . .

attracted huge goodwill and generous sponsors.

It also brought a stream of dedicated gardeners, drawn to Eden as though to a place of pilgrimage. Many people worked for free, five years after it opened, there are still queues of volunteers offering their services.

On that first visit to Cornwall, what I went to see was an enormous, disused china clay pit near the sea's edge: a building site on a colossal scale, with earth diggers and people in hard hats moving all over its pale dusty grey surface.

At the time, the Eden Project, now a registered charity, was costed at a cool £74.5m (that soared to £133.6m when £55.4m more came in from the Millennium Lottery Fund) and was due to be fully open around Easter 2001.

Countless tons of slippery grey china clay were excavated, leaving a crater 60m deep for two gargantuan conservatories . . . giant domes, or biomes, made of layers of film . . . that would eventually house thousands of specimen plants from all over the world and cover an area the size of 30 football pitches.

In the event, the project did open on time and on budget, says Smit. Eden's stated aims were to promote understanding of, and explore the relationship between, flora, fauna, the environment and people. A long walk through the two biomes . . . one big enough to contain the Tower of London . . . that house more than 800,000 plants from the different climactic regions of the world confirmed that it had succeeded.

The next step, according to Smit, is to build a third biome representing the Dry Tropics, "the edge of sustainability", for about £70m.

Most plants in the Eden Project are helpfully labelled, with their uses throughout time . . . often for medicinal or culinary purposes, but also for poisons and perfumes . . .

explained. There are piped jungle and animal sounds, and real birds singing in the lush growth, which has to be drastically pruned by people swinging from ropes. In some "region" it's sweltering, in others pleasantly warm.

There are some very good sculptures and some very bad ones throughout, and there are some bugs, beetles and other wildlife that you would not expect to see in Cornwall.

But all is not perfect in Eden because of the conditions . . . ultimately unnatural . . . in which the plants are growing. Many are prone to heavy pest infestation, so a biome has to be closed off for chemical spraying from time to time.

Beyond the plant life, there are activities at Eden . . . from rock concerts to ice-skating on a rink in winter . . . that are popular with local teenagers.

Eden is to the best dedicated botanic gardens in the world as Classic FM is to BBC Radio 3: it's good that it's there as a popularising and educational thing, but it's not the whole picture.

That said, it was freezing when I visited so all the outside planting was missed.

What a treat, though, to be in the biomes when darkness fell and the lights inside twinkled like stars in a surreal firmanent!

To mark its fifth birthday, usher in the spring and early summer with a fanfare, the gardeners at Eden, with the help of more than 7,000 volunteers, have planted more than a million early and late flowering bulbs across the entire outdoor arena.

Among the bulbs are early and late daffodils, clouds of Anemone St Piran, a river of grape hyacinths, masses of America's favourite early tulip, Red Riding Hood, and then a huge burst of later tulips, including the scented orange Ballerina and the head-turning pink tulip, Barcelona.

Beyond Eden, South Cornwall is fabulously pretty, all soft coloured stone, undulating walled fields and curvaceous hills by the sea. The climate is milder than West Cork and Kerry (being nearer France and not quite on the Atlantic) but, like them, it's good tree-fern, rhododendron, camellia and blue hydrangea country.

A plethora of stone Celtic crosses gives it a familiar feel for Irish visitors, and there is a rich seam of good gardens to be mined in Cornwall.

The Eden Project is near the picturesque and bustling fishing town of Fowey (pronounced Foye), set in Daphne du Maurier country.

Indeed, you can see her summer house, where she wrote Rebecca, clinging to the lower slopes of the wooded hills that rise on the far side of the busy estuary.

The gardens at Heligan are situated some miles away in the equally beautiful country around the town of St Austell.

The first time I travelled to Cornwall was by train from the airport in Bristol, a lovely journey through lush and hilly countryside to the edge of the glittering sea.

This time, I flew directly from Dublin to Newquay, near Fowey, with the friendly South West Airlines, who make the 40-minute hop from Dublin once a day.

Nearby Trenython Manor provides excellent accommodation, which includes a pool, spa, beauty treatments, wonderful grounds with sea views and a herd of fallow deer in a deep wooded ravine.

The cost per night per double room, with bathroom and substantial breakfast, was £125 (negotiable off-season), with dinner costing extra.

DIARY Saturday 25 Feb, Blessignton, Co Wicklow

GARDENER Jimi Blake has launched a programme of gardening, organic vegetable growing outside and in polytunnels (with Lissadell's Klaus Laitenberger), cookery, craft and health courses to be held at Hunting Brook, his home and ever-evolving fiveacre garden and woodland near Blessington, Co Wicklow.

First up on Saturday 25 February is the Complete Beginners' hands-on gardening day, including a guided visit to June Blake's increasingly famous nursery and garden nearby. In May, Jimi will be joined by Helen Dillon for a day of illustrated talks, practical demonstrations and discussions on garden style and planting ideas.

For brochure, booking and more information, contact Jimi, 01-458 3972; 087-285 6601; www. huntingbrook. co jimi_blake@oceanfree. net Saturday 25 Feb, Air"eld Estate, Dundrum, Co Dublin: The Awakening of Spring: a voyage around Airfield estate in Dundrum to see what's stirring in garden, orchard, "elds and hedges takes place from 2.15pm to 4pm. It will be led by Dr Declan Doogue of the Dublin Naturalists Field Club.

Tickets at 5 cover admission to the gardens.