Paul Cooper is a sculptor turned teacher turned garden designer. He has been called the enfant terrible of garden design, or at least of the traditional gardening establishment, which must be reassuring given that he is middle-aged. But the description says a lot about Paul Cooper’s style of work: it has the freshness of youth, which makes it - in the conservative milieu of British gardening - shocking.

Born in Manchester, he is as much a craftsman as an artist, and is engagingly straightforward. There is no hint of pomp or dry white wine in his school of garden design.

Corporate sponsors have snapped him up to design their show gardens, in which his so-called “wacky” ideas are given free rein. The garden he designed for Ford at the Gardeners’ World Live show was built from car parts. His controversial “Cool and Sexy” garden at the Chelsea Flower Show three years ago included back projections of a kissing couple and a hot-air vent in a path to inflate passing skirts a la Marilyn Monroe. His “Boy’s Own” garden at this year’s show was a visual evocation of childhood and adolescence.

Paul Cooper’s critics lash him for producing not gardens but installations, spaces where plants play a secondary role. But this does not worry him. He likes a restrained palette of plants. “If you start from the premise that plants are not necessary, not vital to a garden, then you will be much more discriminating about those you do use,” he says. He admits he is not a great plantsman, and indeed he often works with his wife Jo Matthews, a horticulturalist, on gardens which require a greater plant content. But he is not a plant-hater; he enjoys a catholic range of garden styles.

Above all, Paul Cooper likes gardens with meaning. Sometimes this resides in the display of well-grown plants, but he also enjoys gardens where the meaning is more exclusively in the craftsmanship of its built structure, and in the ideas which the garden expresses.

He also likes those ideas to be contemporary. “Gardens are usually old before they are new,” he says, meaning that by the time a heavily plant-based garden has settled down and matured - say five to 10 years - the ideas which inspired it are old. He finds the idea of age being a virtue in gardens just an excuse, and the beginning of the slippery slope to historicism. “People move house frequently these days. They don’t spend a lifetime in one place. I like to offer them speed, and the chance to have the space they want now, not in five years. In small, urban gardens this is especially easy. I want people to think of gardens as being portable, even disposable. You have an idea, a design, for a while, and then you change it. You do something new.”

Paul Cooper’s gardens for houses, it has to be said, are much more practical than his show gardens. But they are still very high-tech and sculptural by traditional standards, employing lots of steel, wooden decking, plastics, and changes of level. “I like to experiment with materials outdoors, and see what they can do,” he says.

He lists as major influences not garden designers but engineers, such as Eiffel and Brunel. He does not feel his abilities as a designer are any the worse for not having first spent 20 years learning the sister discipline of horticulture. He believes his experience of sculpture is enough.

He taught sculpture for many years at Newcastle and Lancaster universities, and worked on setting up a garden design course at Hereford College of Art and Design, which unfortunately failed to win funding. Today he works primarily as a designer, giving occasional lectures here and abroad.

.As a teacher, Paul Cooper gets greatest pleasure from removing students’ misconceptions about what constitutes garden design, and in seeing their ideas evolve. He likes ideas to be uplifting and witty, even to make you laugh. Which is not, he says, the same thing as being “funny”. He is convinced that a great designer is just as likely to be in his twenties as his sixties, and that the long horticultural haul is not necessarily the road to success.

What will be next for him, after success in garden design? “More architecture, I think. Combining buildings and gardens. It fascinates me.”