We are sitting on a bench in the garden behind his house in a small Norfolk village. While nibbling my tromp l'oeil cake, I am trying to decide if the collection of intriguing objects in front of us is equally illusory. Is that rusticated pyramid by the boundary hedge really made of stone? How about the flame finial on top? "Oh, no, I cut it all out of plywood and old packing cases and stained it blue," he says. Commissioned as a garden prop for the celebrations at Gainsbor-ough's house to mark the bicentenary of the painter's death, this object is typical of George Carter's approach to garden-making. Impressive, but not what it seems. Never mind the materials, feel the effect.
"Surprise is one of the chief delights of a garden," he tells me. "I think of gardens as a form of theatre, you know. You have to create the right atmosphere." There's certainly no shortage of atmosphere here in his own backyard. We set off on a tour, wandering down the geometric pathways between rectangles of lawn, lines of clipped box, poplar trees and hawthorn hedges. It becomes clear that the owner of this garden doesn't hold with the banality of flowers. We approach the packing-case pyramid where I find a row of shell-shaped footlights. "I have those lit up for parties," he explains merrily, "to create a sort of stage." We press on through a gate to an area he calls "the green theatre". A semi-circle of laurel hedge is dotted with (flat, plywood) urns on plinths, painted to give a 3D effect from a distance.
Pausing only to point out the various lines of perspective for which these objects are visual punctuation, he leads on to the next visual joke - a gate fashioned from crossed garden tools - all real this time. So is the obelisk at the end of the hawthorn alle behind it. Just when you were sure you wouldn't, you find flint and mortar rather than paint and plywood. A squiggle of chrome set into the pathway to symbolise a water jet is also deceptive. It turns out to be an inexpensive plant support purchased from a German garden centre.
On past a line of pollarded limes we go, to arrive at a pair of mysterious sentry boxes, a trio of sheds dressed up as baroque pavilions and the hub of all his operations - the workshop.
Stepping inside the enormous (real) barn where he creates his garden effects is more like visiting the prop room of a theatre than a gardener's shed. Next to the electric jigsaw which shapes his wooden scenery, a vast proscenium arch with curtains leans against the wall. A giant striped tent stands in separate pieces, waiting for the summer.
"I'm very keen on the idea of moving things about in a garden, to avoid getting bored," he says. "Why not be flexible and change your garden to suit your mood or the changing seasons?" In his view, garden-owners ought to treat their plots like the rooms inside their houses - redecorating regularly and dressing them up for parties and special events. But the gardens he designs usually involve the simplest of geometric layouts to provide a harmonious backdrop for what really interest him - the garden ornaments. He's also a fan of imaginative lighting effects, favouring floodlights and dramatic flares. Why ignore the garden just because it's dark outside?
It is no surprise to hear that George Carter began his career by designing exhibitions for museums and art galleries. After working for the Geffrye Museum in east London (where his art deco room survives) and for the Sainsbury Centre at the University of East Anglia, he turned his attention to the great outdoors. His slot-together sculpture adorned the first British garden festivals in Glasgow and Liverpool and he began to attract a variety of clients with gardens great and small.
Tiny urban backyards were soon laid out like Versailles and their sheds disguised as splendid pavilions. Aristocratic or wealthy clients ordered whole gardens, more ordinary gardeners bought a bench or a (fake) urn. Even the down-to-earth Geoff Hamilton of the BBC's Gardeners' World featured (and imitated) his plywood obelisks and Palladian chicken coops. People have been happy to let him have fun at their expense.
This playful attitude is one of the main reasons his admirers now label his work "postmodernist". Does he agree with them? "I'm all for ransacking history and taking the bits that one likes," he says, "so I suppose you could see it that way. I enjoy visual jokes but I don't think I'm creating a pastiche of the past."
While some of his fellow garden designers may see his work as narrow and historically limited, many others passionately defend it. The designer Jill Billington insists he is "never nostalgic" and praises his lightness of touch and the confidence with which he handles space. "He's tremendously decisive," she says, "and achieves real fusion of hard and soft with ornaments and plants used as walk-in sculpture. The way he uses light - daylight and artificial - creates strange, ethereal and powerful images." The staunch modernist David Stevens is also a fan, citing his "strong architectural bent" as a particular advantage.
It is true that George Carter's heart belongs to the 17th-century garden with its austere architectural lines subverted by statues of baroque river gods, gilded automata, joke fountains and early theme-park grottoes. While he also enjoys Tudor and medieval styles, his favourite British gardens are the strictly formal ones at Ham House in Surrey and Hazelby House in Berkshire. Abroad, he rates highly the drama of Schloss Heidel-berg in Germany, Bel Oeil in Belgium and the Villa Marlia near Lucca in Italy.
It is also true that he detests any notion of a garden as natural, environmental or picturesque. "It's a false notion," he insists, "because gardens are always artificial. Before we invented the idea that a garden should imitate nature, we had a much more simple and honest approach." In his view, the picturesque and landscape movements of the 18th and 19th centuries did us a great disservice. "They actually invented the sentimental way we see nature, which we are still clinging to today."
His gardens are too knowing and tongue-in-cheek to be tied to the past, however. It is clear, whether wandering around his own garden or flipping through his portfolio of work for clients, that he has an eye to the future and is filtering history through completely modern eyes. His "sampling" of past styles is closer to current trends in pop music, fashion and graphic design than to dry historical reconstruction. His training was in sculpture rather than horticulture and he refers to his works as "installations" or "performance art". He sees his type of approach as one of the strongest strands in garden design in the present and into the next century. If, when wheeling his trolley through the Supermarket of Style, he generally ignores the shelves marked "Post-1750", he feels surprisingly strong links with modernism.
"People find that early style which I love so alien that it strikes them as modern," he points out, "and there is a connection. Early modernist gardens harked back to past formality in their geometry and discipline with designers like Thomas Church and Luis Barragn. Unfortunately, modernism never really caught on in this country." While the Bauhaus school decamped to California between the wars to create some famously modernist gardens, English architects began siting futuristic buildings within flowery Gertrude Jekyll-style plots. It was a failure of nerve which, he believes, has dogged British gardens ever since.
"I agree with people who say our garden design is 50 years behind the times," he says, fingering a gilded lavatory ballcock masquerading as a finial on one of his pieces. "In fact, it's more than 50: innovation dried up with Gertrude Jekyll and her artist's-eye borders. There are much more exciting things being done nowadays in the gardens of Europe and America." He sees one solution to this problem in better education in the visual arts. British children, he says, should be encouraged to understand and enjoy the arts - fine and applied - from an early age. That way they might grow up to appreciate garden-making as an art form of the future, just as it was in the past.
He is sure it would also help if an alternative to the Chelsea Flower Show could be established, as a forum for really innovative garden design. Such shows exist in Europe and the USA, but here would need to be run by a body other than the plant-centred RHS, he feels. "It would help to make the public more confident about trying new things, too. People could see the endless possibilities of owning a piece of land and having a completely free choice in what to do with it. They could do anything they liked, as long as it meant something to them. I'm all for people doing bizarre things in gardens."
He certainly intends to carry on being bizarre with his garden installations. In his own garden he is planning a spectacular water feature, involving major hydraulics, to include a fountain that rises up from beneath a lake, opens up like a flower and sends jets of water in all directions. For parties, clients are now commissioning him to construct arches, temples and amphitheatres made from bales of straw. These make an impressive sight during the day and an even more awesome impact when they are set on fire as darkness falls.
If your garden is big enough, why not? "It's the cheapest way to create a piece of theatrical architecture," he insists. "And it looks even better if you have fireworks afterwards."
Adventurous readers can contact George Carter at Silverstone Farm, North Elmham, Norfolk, NR20 5EX (tel: 01362 668130). !
NEXT WEEK: The ecological garden