When Robert Spano was invited by the BBC Scottish Symphony Orchestra to conduct a portrait concert of Osvaldo Golijov he was also asked which other contemporary American composer he would like to include in the programme. For Spano, chief conductor of the Atlanta Symphony Orchestra and something of a specialist in this repertoire, Michael Gandolfi seemed an obvious choice.

"There is a noticeable new aesthetic phenomenon in this generation of American composers which is writing tuneful, tonal music that also contains influences of world music, popular music or sometimes both," he explains. "Golijov and Gandolfi fit this mould really well, as do a couple of other composers: Jennifer Higdon whose hugely popular Blue Cathedral was performed by the RSNO last season and Christopher Theofanidis. These composers all write completely different music yet there's a thread that links them together."

Another reason that Spano opted for Gandolfi's music and one of his large-scale orchestral works in particular, was its local connection. The Garden of Cosmic Speculation was inspired by the actual garden of the same name that was created by husband-and-wife architects Charles and Maggie Keswick Jencks in Dumfriesshire. Anyone who has seen the large landform sculpture on the lawn of the National Gallery of Modern Art in Edinburgh will be familiar with Charles Jencks's work; in Scotland, he is perhaps most closely associated with the Maggie's Cancer Caring Centres, which he and his wife set up before her death from breast cancer in 1995.

The Garden of Cosmic Speculation is the Jencks's private garden, created in the grounds of Maggie's family home, Portrack House outside Dumfries. It is only open to the general public on one day of the year as part of the Scotland's Gardens Scheme and, by happy coincidence, that day just happens to be this Sunday, the day after the BBC SSO performs Gandolfi's work in Glasgow. Gandolfi hadn't actually visited the garden when he wrote the original four-movement suite in 2004; it was seeing Jencks's book about it that sparked his imagination.

It was only after he visited Dumfriesshire and met Jencks that the piece was expanded into its current 11-movement form, which was premiered and subsequently recorded by Spano and the Atlanta Symphony Orchestra last year. In Glasgow, the BBC SSO will perform eight movements. "Michael's intention was to write a piece in which any possible combination of movements is achievable," explains Spano. "The piece that inspired him in this respect was Prokofiev's Romeo and Juliet; there are three existing suites of music from the ballet, but usually conductors mix and match. In choosing these eight movements, we tried to find a good balance of continuity and surprise."

While the wave-like grassy banks, curved ponds and sculptural features of the Garden of Cosmic Speculation are intended to provide a visual metaphor for the discoveries about human life and the universe made by modern science, each of the movements of Gandolfi's piece corresponds to some particular facet, be it botanical or structural. One such feature is the Universe Cascade; a stairway embedded in a hillside, whose landings are inscribed with symbols of events in the history of the universe beginning with the Big Bang and ascending to the present day. Gandolfi echoes this structure by tracing the development of western music through a series of quotations, starting off with Gregorian chant and progressing via some of the major figures in music history: Josquin, Palestrina, Bach, Beethoven, Stravinsky et al to Miles Davis and Steve Reich in the late twentieth century. It is, says Spano, an "accelerated view of music history".

Neither Gandolfi nor Golijov is a familiar name in Scotland, but the latter, in particular, is a major figure in the US where his eclectic style - with its influences ranging from Cuban drumming and tango to klezmer - has found him a huge following. Gandolfi's references are more rooted in the classical tradition, though shot through with an element of popular music reflecting his previous career as a rock guitar player.

This music has its detractors, however, particularly on this side of the Atlantic, where the new wave of American music has been criticised for having too much colourful surface and not enough substance. "I suppose there's always been a prevalent attitude, particularly in academia, that if a piece is popular then it can't be any good," says Spano. "I think what's telling for me about this music is that every time we perform it we find new things; it's always a new experience. I think that's testament to its quality; that one's perception and understanding of it is enriched over time."