Working within a set budget (Chelsea please note) and a set space of about 250 square metres, 30 creative people - designers, architects, dreamers, artists, even some gardeners - have installed gardens, which stay in place for the season. Each space is separated from the next by a well-established beech hedge. This is important. Each garden benefits from being distinguished from its neighbour and the hedges also provide a feeling of stability, anchoring them - too often, show gardens look as if they have been dropped by mistake from a passing helicopter.
The walk from chateau to show gardens is a kind of initiation. It puts you into innovative mode. The path winds through woodland which sits well with the arbours, tunnels, suspension bridges and drawbridges designed by Jean Lautrey. Steel reinforcing rods have been used to make the graceful Gothic arches, the rods splayed at the base and bunched together at the top with bindings of wire.
The designer's suspension bridge is a triumph. Slats and rods of scrap iron are wired together to make the bridge, which is slung from further splayed supports of reinforcing rods. It may sound like a Steptoe creation, but it's restrained, elegant and, in this woodland setting, appropriate.
The concept is not new. In construction, Lautrey's creation is like every bamboo, creeper or wooden suspension bridge you have ever wobbled over in Asia or the Caribbean. Here, it is in futuristic mode, the steel rods rusted to a colour that almost disappears into the background.
Each year there is a festival theme. They have had - Is Technology Poetically Correct? (it sounds better in French) and Water Water. This year it's Rien que des Potagers, though actually there is plenty that has nothing to do with potagers.
But Edouard Francois, a French architect-planner and Duncan Lewis, a young designer, who trained at the Royal College of Art, took the brief seriously in their Potager Aquatique. They built a soft greenhouse of transparent plastic, supported by a geometric framework of strong bamboo poles. The outside of the structure is screened by groves of livebamboo, such thickly planted phyllostachys that you can't see the greenhouse until you are practically in it. It covers a big, angular pool, which is crossed by intersecting board walks. Taro, water chestnut and lotus grow in the water. And marrows and gourds scramble up the bamboo supports.
I like this garden because it is unaggressive, the whole insinuating itself gently into a growing envir- onment rather than being thrust bossily upon it.
The Potager Portugais, from the Portuguese potters Teresa and Felicia Louart, which was planted by France Rossignol, a Belgian student of landscape design, is tyrannised by its tall, hexagonal ceramic columns made from tiles of brilliant blue, yellow, pink and green. The real problem with this garden is itscolumns having little to do with the remainder of the design. And, set against the vividly painted carrots, lemons and gourds on the tiles, the real fruit and vegetables look tired and washed out.
My prize for style and concept goes to the Potager Nomade, made by French architect, Patrick Nadeau, and two designers, Joelle Alexandre and Vincent Dupont-Rougier. The idea of a portable potager sounds contradictory, but here was an elegant cube, perhaps eight feet square made from bleached wood with stainless steel fittings.
Each of the four sides of the cube fold out to make four aprons, held level by stainless steel hawsers. One has a pleated plastic cover, rather like a pram hood, which makes a mini greenhouse for aubergines and red peppers. Huge tomato plants, bearing at least four times as well as my own tomatoes at home, occupy a second apron, and lines of salad vegetables, alternating with parsley and basil, fill the third. On the fourth part is a deck-chair covered with bright orange canvas, shaded by a canopy of the same material which unrolls from the ceiling of the cube.
The point of all this is that the vegetables grow hydroponically, without soil. On the salad "apron", strips of growing medium, wrapped in white plastic, alternate with strips of wood. The vegetables and herbs are planted through the plastic, in the way you plant using plastic as a ground- covering mulch. It might look too clinical and smack too much of the laboratory when first planted, but by the time I caught up with it this week, the plants had camouflaged the underpinnings. They were growing beautifully - and hadn't become sacrificial victims to an idea.
The water for the hydroponic system is drawn up from a tank, aerated, "fed", and then funnelled around the plants before being filtered of impurities and returned to the reservoir. All the work has been beautifully executed. The wood is as smooth as silk, the joints fit perfectly, the steel bolts and wires (they looked like yacht fittings) have no snagging edges. In a tiny space, without soil,these designers have created an oasis of plenty. It is innovative, heartening and beautiful. You can't ask more of a garden.
The prize for excelling in wit, I would hand to three young Scottish landscapers from Scotland's Department of Natural Heritage. Taking the line that if you can't beat a cliche, you have to embrace it, Nigel Buchan, Frazer McNaughton and Lumir Soukup, designed a Tartan Potager. It has overlapping stripes of green and pewter-coloured cabbage, red-stemmed chard, and black curly kale,as well as beetroot and crimson salvias.
Here, mulching alone becomes an art form. The designers have used tiny fir cones, shattered slate, mussel shells and moss, spread in thick, separate layers under their plants. And they have built a tower of mesh cages, each of which holds "a piece of Scotland" - either peat blocks, or dried heather, or pine logs or seaweed.
As for booby prizes - they could be given out as equally freely. Ugliness and pretension have sometimes combined to spectacularly awful effect. I think of the Nebelgarten made by Peter Latz and associates, German landscape architects. The information here noted that the company's last project had been the rehabilitation of a metallurgical factory. That might explain why blasted earth is in the ascendant, with a few dying plants cowering between sheets of stone. Every so often, steam shoots up from nozzles set in this graveyard of hope.
Shodo Suzuki, a Japanese landscape architect, has contributed L' Archipel symbolising "the state of crisis in Japan". I don't know about Japan, but the garden certainly seems to symbolise a state of crisis in Mr Suzuki's creative imagination. Fortunately, raked gravel is always soothing, so you could concentrate on that, and on the comforting fact that this is the only work the landscaper has done outside his native country.
For freshness and ingenuity, Chaumont is unparalleled I had never seen olive stones (these were from Nimes) used to top-dress paths. They are wonderful to walk on - slightly springy. Broken terracotta, also used for paths in some of the gardens, is harsh and uncomfortable.
I loved the zinging colours too, especially in India Song, by French designer, Eric Ossart. A canopy of orange and pink, supported on poles of bright fuchsia pink, covers the path through his garden. The garden itself, shallowly terraced, is planted (or painted, as Ossart put it) in brilliant strips of the same colours - with amaranthus (celosia `Feather Purple'), dahlia `Wetzel's Daughter', gladiolus `Fidelio', gomphrena, purple morning glory, pelargonium `Maverick' and the brilliant French marigold `Zenith'.
In Britain, we probably have more garden designers per head of population than anywhere in the world. But where is our showcase? We need a Chaumont too.
The International Festival of Gardens is at Chateau de Chaumont, 41150 Chaumont-sur-Loire. From Tours, take the 152 along the north bank of the Loire, towards Blois. Cross the river at Amboise and continue on the D751 to Chaumont. The TGV will get you to St Pierre-de-des-Corps, where you can change for Blois. Local trains stop at Onzain, 3km north of Chaumont. The festival is open each day (9am until dusk) until 24 Oct. Admission 48F. Telephone: l 00 33 2 54. 20 99 22