Edinburgh Festival: Mulch ado about nothing: Toby Gough's alfresco play on a tyrannical botanist leads its audience up the garden path. Sabine Durrant reports

Welcome to the secret life of plants. In the Royal Botanic Garden, Toby Gough, Theatrum Botanicum's director and deviser of Linnaeus - Prince of Flowers, is tugging at a clump of alchemilla mollis and shaking like a leaf. He's suffering from a combination of cold (bare legs, shaved head, an outdoor venue) and fear. A few shrubs away is a scene of apparent chaos, a muddle of costumes and performers, of bits of paper in the wind, of shouted enquiries - 'The giant banana? Where does that go?' - and irritable exchanges - 'We can't use the rock garden' 'Why not?' 'Because we can't'. Everything isn't coming up roses. But at least it's not raining.

At last year's festival, the venue Gough was running went bankrupt, so understandably he's decided to do things differently this time round. You can just see him in his college room (at 24, he's recently graduated from Edinburgh University), thinking: 'Um . . . two-hander set in a kitchen diner? One man show on the hoof? Nah, to hell with it, why don't I book 40 actors, a 30- strong orchestra, rope in a few Royal Court Musicians of Uganda, some dancers from the Brazilian Theatro del Arte, get a pounds 6,000 personal bank loan and take over somewhere really, really big - the Botanic Garden even]' That's pretty well what he's done. It's an astounding achievement. Gough and his producer Melissa Fitzgerald have devised 'an 18th-century travelling masquerade' that moves around the gardens - across rolling lawns, under a 30ft beech hedge, through herbaceous borders you could get lost in and along - not in - a rock-garden the size of Wembley Stadium.

His subject is the 18th-century Swedish botanist Carl Linnaeus who, most notably, discovered the sexual characteristics of plants. 'He was the greatest botanist of his day,' says Gough, speaking very fast through quivering lips. 'Eighty years before Darwin, he could understand the whole of nature, how it all linked up in one great chain. He classified 4,400 species of animals, 7,700 species of plants. He was a great traveller who was on a massive quest to find the truth, he was the first man to put man inside the animal kingdom. He was Shakespearian, Ibsen-esque . . .' Gough trails off a bit and then suddenly remembers a clinching detail: 'He knew about rings in trees]'

For all that, Linnaeus comes out of Linnaeus rather badly: here he's a military tyrant with a mad face, a bald head and a magician's gown who banishes the small wild marigold, who rails in old age about the world and his achievements, who's horrid to his wife. Clearly, his classifying, ordering mind goes against the grain of the director, who admits: 'I can't write scripts. I can talk. I talk to someone and they write it down. The show has still to fill and grow. At the moment it's in an organic state.'

Not that the production, he insists, isn't intricately thought out. 'The theatre should fit with the different environments,' he explains. 'The audience travels into the fairy- tale woods for childhood, into the classical gardens for order, to the greenhouse for ambition, and then the wide-open spaces for travel.' Great on paper - or in words - but in performance the show is chaotic, a mad pageant of flirting flowers, bald scientists and inventive props (a huge book that eats flowers, a boat on wheels, a magnificent swan). It's exuberant and charming, but needs a good hard prune. On the first night, with 150 people chasing the actors down the garden path, it was rather like being on a guided tour through a stately home, endlessly finding yourself one room behind the courier. Two middle-aged women lost their concentration very early on. 'Well it just shows how insensitive people can be,' one was saying to the other. 'Why doesn't he go into the city then if he's so high-powered?'

Gough, who's about to embark on a PhD on The Use of Performance Space in Carnival Forms, probably wouldn't have minded. The play, he says, is 'particularly timely in view of the Criminal Justice Bill'. At the very least, Linnaeus is a celebration of the right of a large number of people to gather in a public space.

At the Royal Botanic Garden, West Gate, Arboretum Place, 15-27 August (not 21 Aug), 8pm- 10pm. Tickets at the gate or at the Fringe box- office: 031 226 5138 (Photograph omitted)