WASHINGTON - The frame is stooped, the gait a little halting, but the spirit glows as strongly as in 1948, when Susana Valeria Rosa Maria Gil Passo first caught the eye of the composer William Walton during his fateful visit to Buenos Aires. They married eight weeks later to form a lifelong partnership.

She was in Washington last week, giving a number of public and private appearances in connection with a performance of Walton's choral music at the Kennedy Center.

But she was an ambassador as well for the music of gardening, and for the symphony of plants she calls La Mortella. Her hillside garden on the island of Ischia, in the Bay of Naples, is now bursting into bloom with the jade vine, which her head gardener calls “the most beautiful climber you can think of.”

The camellias are lingering, the hardy geraniums are about to flower and the jacaranda tree will soon follow.

In the 23 years since her husband's death, Susana Walton has taken the garden to new heights, adding, for example, a lakeside Thai pavilion and an orchid house, and turned her Eden into a beacon of horticulture by opening it to the public.

Her book on its creation (“La Mortella: An Italian Garden Paradise”), published in 2002, reveals a place lush in its water features, palms, tree ferns and cycads. It also lays out an amazing story of transformation of what was once so barren and dry a piece of ground that when the couple first toured it with their friend Laurence Olivier, he counseled against buying “a stone quarry.”

But something drew them to the site, and they named it for the myrtle that covered the hills. Olivier returned to see the property transformed and as a testament to what can be done if you stay in one place long enough, have a vision, and are not put off by such small inconveniences as a lack of money or uncooperative local bureaucrats.

Her Washington visit, organized by the Washington Chorus, included visits to gardens in Georgetown.

At Tudor Place, for instance, she found the early stirring spring agreeable, but her biggest task was to try to keep her mind off La Mortella and not fret about all the seasonal tasks that dedicated gardeners worry about.

Susana Walton had expected to make her life in England, where Walton was already an established cultural figure after World War II, but he told her he needed a warmer, sunnier climate and a place where he could work in solitude.

He was so sensitive to sound that he had a valve in his music room to turn off a fountain when it bothered him.

By that point La Mortella had the luxury of running water, but when the Waltons began the whole island was without municipal water.

Another early visitor to the arid, five acres of rock, landscape architect Russell Page, told Susana Walton to forget about ponds and fountains and forming a verdant paradise at La Mortella.

A top-flight plantsman who took elegant settings and made them better, Page suggested she go with the type of silver-leaved Mediterranean plants that grow in a place where there is little or no rainfall for five months of the year.

For 12 years she put his plan into effect, aided by her innate gardening instincts to improve the soil. The site had one thing going for it, at least at its base: a thick layer of rich volcanic soil.

And one of her first acts was to arrange for the organic refuse from the neighborhood to be composted on the site. She screened it and worked it into the plantings.

By the time Page returned, the very nature of the garden had altered. Water had been piped to Ischia from the mainland about five miles away: After many thousands of years of settlement, the island was no longer reliant on wells and cisterns.

This development allowed Page to design three additional fountains and, much later, a decorative canal in the same reverential way that Arabian and Persian gardens honor the rarity of water in a dry land.

In the lower reaches of the garden, trees that Susana Walton had planted were beginning to provide the shade that would permit a different type of flora. She chose the American tulip tree, which found La Mortella just cool enough to flourish. The temperatures come close to freezing in winter, sometimes too close, forcing a major annual undertaking in November to cover and protect the most vulnerable subtropical beauties, including the lemon trees.

Susana Walton attributes the lush transformation of the garden to a single act. When her husband was touring Australia and New Zealand in 1964, he sent back three tree ferns in a shoebox. These flourished thanks to careful siting and coddling with water, and Page changed his mind about La Mortella being a dry place and urged the mass planting of the ferns. In time, she took to the appeal of other primal subtropical plants, including the palmlike cycads. Visitors to the site marvel at the health and vigor of the plantings. It would be easy, given Susana Walton's flair, to think they are responding to something more than just green fingers. As for the palms, for instance, she says, “You have to wave at them when you go by because they think you haven't paid attention.”

She said that in their early days at La Mortella, her main mission was to create an environment that nurtured her husband's work.

As the garden developed into something special, it became its own driving force and is still a work in progress for its 80-year-old matron. Her husband's ashes are interred in a rock at the top of the garden.

Today, the 60,000 visitors from April 1 to Nov. 15 find an aquatic greenhouse for growing the Victoria lily, the world's biggest waterlily and one that continues to dazzle plant lovers long after its arrival from South America. Like Lady Walton herself.