GARDENING / A composition in many scenes: Designing the gardens for Glyndebourne's new opera house was a process fraught with high drama, says Mary Keen

LAST WEEK was the season of the instant garden. At Chelsea, around 30 were assembled for viewing, which have all now been dismantled. One of the judges of these displays, John Sales, the National Trust's chief gardens adviser, gets my quote-of-the week award. 'A garden,' he says, 'is a process, not a product.'

Being in the business of designing gardens as well as writing about them, I spend a lot of time explaining to clients who expect Chelsea standards that there is no such thing as a finished garden. Besides, the show plots that burst into instant blossom are fabulously expensive to stage. One national newspaper allocated pounds 150,000 for its patch, of which now no trace remains. No private owner could afford to spread money that thickly on areas a hundred times the size.

Recently, however, I have had to soft-pedal on the process versus product line, because I have been involved in designing the approach gardens for the new opera house at Glyndebourne, which opened last night. If 1,200 people are arriving excited and critical about changes to a well-loved institution their first impression is what counts. As the season continues, around 100,000 opera goers will expect to see something for their money, especially those who have generously contributed to the appeal for the new building, which has received not a penny of subsidy from any government body. Some soul mates also gave money specifically for the gardens and they perhaps will expect to see less of a product than the process of a growing garden.

Unlike the Chelsea exhibitors, we had four months, rather than four weeks, to assemble the gardens and if the scope was somewhat larger than that of the average Chelsea plot, the funds available were only marginally higher than a top show garden's budget. As Americans say when the going gets tough, 'the learning curve was steep'. For most of the time we wore hard hats and learnt to dodge the crane. It rained incessantly, so the heavy machinery needed to move old apple trees into key positions could not be used, forcing us to make do with smaller trees for fear of damaging the ground. But damage was unavoidable, because of the shortage of time. Soil compacted by a combination of other machines and even more rain had to be replaced. Then there was the problem of the ramp up which wheelchair users will roll to the opera house with a view over the Sussex downs.

The ramp turned out to be too steep for the building inspector. A rise of 1 in 12 in is apparently unacceptable unless landings are provided, so we curled it round further and now the view is even better. The fragrant aquilegias that should have been out for the first night were eaten by sawfly caterpillars (like my gooseberries at home), and the sulphur yellow evening primroses never arrived. The standpipes for watering - when it stopped raining, which it did as soon as planting began - lacked the pressure to turn a sprinkler on to new turf and trees. Now I know that you can run a hose off a fire hydrant in an emergency, provided the water is metered. Some of this new knowledge acquired from a roller coaster of tribulations may not come in handy for the domestic gardens that are normally my line, but it is not every day one is asked to design the approaches to a private opera house.

In spite of the scale of the operation and the need for it to be all right on the night, the way the job was tackled was always more in sympathy with the process philosophy than the product option. When things went wrong, our team talked the problems over. Unlike some clients, Lady Mary Christie, the chatelaine of Glyndebourne, was involved at every stage of planning and planting.

She did not want to be presented with a garden that was not in the end her own and she also felt - as I do - that the people who were to maintain the garden should have a say in the way it was arranged. Chris Hughes, the head gardener, and Graham Harvey, his number two, came to all our meetings, even those indoors, with Michael and Patty Hopkins, the architects. The hard landscaping and practical support came from Nick Lawrence of Landscape Management Construction, one of the few contractors I know who makes life easier rather than harder for the designer. All the planting was done by the existing four gardeners at Glyndebourne, Chris and Graham with Kevin and Giles, and sometimes me. Although we made plans, when it came to setting out plants their places changed, as they do in process, rather than product, gardens.

On the former tennis court, old bricks and paving stones surround huge beds with the resited apple trees in seas of moonlight plants. This is a last act of Figaro garden, a green yew room filled with pale violas and campanulas and misty blue agapanthus. One way in to this garden lies through the Mildmay garden, where a new restaurant forms one side of a walled enclosure with beds of roses and irises and this year the bluest of sweet peas, Noel Sutton. More new Glyndebourne than old is the Bourne garden, a steep dell with crazy staircases in Grand Opera mode sweeping between dramatic plants like giant angelicas, paulownias, rhubarb and foxgloves.

The steep bank that goes down to the front of the opera house had another source of inspiration, an Italian ravine; here, large magnolias, ilex, acacias and bushes of box will grow. Chris and Graham proved brilliant at sticking to our chosen themes, which is what for me always makes a garden work, and by the end they knew instinctively what plants were right for which areas. In a continuing process they will add to the ideas we all had together on so many cold and rainy days, while the bulldozers rumbled and the crane swayed overhead. Because of their commitment it will continue to be a real garden for the people who live and work there, long after the fanfare of the first-night audience, because in the end it is gardeners who keep the process going.-