Dan Colen is a hard artist to pin down.

His work, aesthetically, trampolines from one discipline to another, ranging from a toppled row of Harley Davidsons to Disney pastiche, from paintings that look as if they have been made from guano to paintings that really have been made out of flowers.

"People don't know how to join all the bits up," says curator Paul Nesbitt, who is presenting Colen's first major solo show in Scotland at Edinburgh's Inverleith House. Nesbitt, who admits he was stumped by the dominoed motorbikes until he took Colen aside and got him to explain what he was doing, is evangelical about the once-controversial American's work. "This show is showing what Dan is like when you join all the bits up. You can understand what he's saying much better."

Born in New Jersey in 1979, Colen studied painting at the Rhode Island School of Art and Design (2001) before a breakthrough year in which he exhibited at the Whitney Biennial and the Royal Academy in London (2006). If it was his drug-fuelled antics that gained him column inches for some years subsequently, he is now more concerned with the nature of his art. "I spend my daily life trying to distil what art is," Colen tells me when we meet in the gallery some days before the exhibition opens, his sought-after flower paintings vibrant on the walls among the detritus of installation.

When Nesbitt approached Colen with the idea of mounting a solo show in the heart of the Botanic Gardens, Colen was swayed by the catalogue from Cy Twombly's 2002 flower show. "I knew then that this was the place for the first flower show," says the artist, who has never exhibited a body of his flower paintings before. "But it developed into something a lot more."

The Illusion Of Life, a title based on a seminal Disney animation book that Colen has been collecting in various editions for years, is a typically wide-ranging collection of work. Touring the gallery mid-installation - filled with remarkably tall Americans wielding electric screwdrivers (the equally lofty Colen's artistic collaborators) - the "bits", as Nesbitt might call them, include a ghost couch floating beneath a fortune-telling Magic-8 ball, a pair of spatted shoes dancing on the ceiling and a room full of gaudy, blown-up whoopee cushions arranged on chairs and pedestals that the artist has made himself.

A woman is carefully constructing what will be an acme house of cards; a man is assembling a cardboard city for a zombie clown that someone has forgotten to put on the plane; and Colen himself is fumbling with a self-spinning Coke bottle that is, somewhat truculently, refusing to spin.

"None of this stuff is really set up yet," he says as he launches into a guided tour. "A lot of the show has to do with trompe l'oeil, with things not being what they seem, or in fact being exactly what they seem." Subtly, humorously, there is the idea, too, of art generating its own power - an unseen essence that fires between the object and the viewer - whether in the air dispelled from the whoopee cushions or the movement of a curtain in front of a fan.

If the supernatural and a sense of "mystery and wonder" will imbue the show, the overriding implication - at least on this early viewing - is of loss. In the middle of all this nascent construction, it is the flower paintings that stand out - not surprising given that they are, after all, the only finished works on display at the time. Flecked with myriad colours and psychedelic smears, these vast pieces are created by grinding and pummelling petals into the canvas in a physically gruelling process that bonds, to a certain extent, the flowers with the canvas.

And yet they are a transient thing, too, not only susceptible to potential degrading over time, but largely made from "grave flowers", the artificially dyed flowers sold by New York delis. "I've always avoided trying to make the paintings a sturdier thing," says Colen. "They're all dead flowers, and there is something in flowers and death, in flowers dying, that is a big part of the work."

It comes back to the idea, for Colen, that painting is about "the marks that are left, the traces of presence". It is just that sometimes - courtesy of zombie clowns and self-spinning bottles - they are left a little more literally than others.

Dan Colen: The Illusion Of Life, Inverleith House, Edinburgh (0131 248 2971/2849 at weekends, www.rbge.org.uk) until November 24