Ten thousand lead-crystal pendants dance beneath a cloud of scrunched-up chicken wire. Suspended on nine poles above a fancy patio, the art installation “Cloud Terrace” captures the stark, cold winter light and throws it back in flashes of color, intense bursts of orange, scarlet, indigo. John Beardsley has been drawn to this spectacle over and over since it went up in April and has found it to be a siren with many songs. “The piece has different moods,” he says, striding toward it. “When the shadows come, the crystals are like dew on a spider web. When the sun comes out . . .” The sentence is unfinished, but we know what he means. It’s dazzling.

Beardsley’s official title at Dumbarton Oaks is director of garden and landscape studies, but he is also playing the role of impresario: “Cloud Terrace” is the third in a series of temporary, edgy installations by environmental artists that Beardsley has organized since he was appointed in 2008. A fourth will be unveiled later this year. ¶ The installations have been widely although not unanimously praised. More remarkable is that they are there at all: Until Beardsley came to the Harvard University research institution in Georgetown, no one had dared to use the historic and sanctified landscape in such a way.

The installations have helped increase the number of visitors to the garden and galvanized dozens of volunteers. Most of all, the artworks have breathed new life into a garden that had become, perhaps, ossified by its own historical significance.

“It’s made such a difference in the way we think of ourselves,” said Gail Griffin, the director of gardens and grounds.

The first of the series, “Landscape/Body/Dwelling,” by Charles Simonds in 2009, featured placements of weird figurative and architectural clay sculptures staged indoors and out. The second, the 2010 “Easy Rider,” by Patrick Dougherty, consisted of 15 woven twiggy sculptures rising like tornadoes around the formal clipped hedge of the Hornbeam Ellipse.

Artforms named "Easy Rider" by artist Patrick Dougherty, installed at the Hornbeam Ellipse at Dumbarton Oaks in 2011. (Anatole Tchikine)

“Cloud Terrace,” occupying most of an overlook named the Arbor Terrace, is the work of artistic partners Andy Cao and Xavier Perrot. The bejeweled cloud of wire is held above an existing parterre, reworked to hold a reflecting pool. The piece was due to come down in November but is still popular and looking good and will be around until April, barring destructive weather, Beardsley said.

The estate’s 10-acre garden was designed between the world wars by pioneering landscape architect Beatrix Farrand for her patrons, Mildred and Robert Bliss. In 1940, the Blisses gave the property to Harvard. Its mansion and attendant buildings house centers of pre-Columbian and Byzantine art, a related museum and a library of rare garden books. The garden synthesizes Italian, French and English styles in a highly crafted series of spaces, many of them formal in character and layered with symbolism and narrative.

The Oxford Companion to the Garden describes it as “one of America’s most celebrated gardens,” making the Simonds debut, in particular, a brave choice for Beardsley.

Simonds’s sculptures examined cycles of growth and decay. Much of it came from the clay earth, including miniature cities and, in a video exhibit, Simonds himself, emerging naked from a New Jersey quarry. Among his garden pieces was a plaster head set in the Rose Garden whose blank stare and grimace instilled an unsettling anguish.

“The grimacing faces were perceived as threatening or just ugly,” Beardsley said. “What appealed to me was that it connected to a dimension of gardening that is grotesque.” That is a subtext of the garden at Dumbarton Oaks, Beardsley argues, pointing to the animalistic head of a river god that Farrand and Bliss installed in the Arbor Terrace.

Beardsley found himself up against a view that the garden was enough of an artwork itself that it needed no embellishment.

The eminent and outspoken landscape historian John Dixon Hunt, who once held Beardsley’s position at Dumbarton Oaks, wrote in Landscape Architecture magazine that “it is not clear to me why such an iconic garden needs to be subverted with material and forms alien to it.”

Most of the unhappy visitors to the Simonds show were content to complain orally or in written comments, although one person was driven to smash the nose of the head in the Rose Garden (where the Blisses’ ashes are interred).

Walter Howell, a gardener who has helped with the installations, said he imagined the miscreant not a youthful vandal but “an elderly patron who was whacking it with their cane.”

Beardsley says it is wrong to think of a garden, even one as historic as Dumbarton Oaks, as something static and unchanging. Plants grow and die here, including big old trees, and the design, too, has evolved. “No one who has ever worked in a garden thinks of it as finished,” he said. He notes that some of the garden’s most signal spaces — the Hornbeam Ellipse, the Pebble Garden — took their present forms after Farrand retired.

The Arbor Terrace features the shady retreat of a magnificent wisteria-clad teak pergola alongside an open terrace framed by decorative masonry and ironwork and surrounded by tall pear trees. Farrand designed it as a place for a herb garden. Her successor, Ruth Havey, reworked it with rococo flourishes. It was always a hot and exposed site, which is why Cao and Perrot wanted to place their cloud there, and because the scale was so right.

The works are not mere sculptures but are designed to engage their specific site. “Easy Rider,” Beardsley said, “was the most gardenesque, organic.” “Cloud Terrace,” he said, leading a visitor beneath its prismatic crystals, “is the least organic, the most ornamental and yet seems very natural in that it intensifies your experience of light.”

The work took three weeks to build. (“Easy Rider” involved 66 volunteers and took four weeks to assemble.) Cao, whose office is in Los Angeles, and the Paris-based Perrot worked with a smaller group of volunteers and directed the most artistic among them to position and hand-tie the Swarovski crystals, which are on loan from their maker.

The temporary nature of the installations, Beardsley said, not only seeks to mollify the garden purists but also makes its own artistic point. Gardens, by their nature, “are the site of all kinds of temporary activities: theatrical events, parties or trysts or intrigues of one kind or another,” Beardsley said. “They are socially dynamic.”

The garden and museum at Dumbarton Oaks are open to the public, but the academic institution doesn’t go out of its way to advertise them.

Much of Beardsley’s career focus has been on contemporary environmental art, a different animal from Farrand’s work, which inherently looked to historical antecedents.

Yet the second and third installations in particular seemed to have augmented rather than diminished the garden at Dumbarton Oaks and forced a reevaluation of Farrand’s masterpiece as being wholly immutable. “Most poignantly for me,” said Griffin, “I have missed them when they were gone.”

“We don’t want the gardens to be fossilized but rather something living, and if the temporary installations help to keep them alive, that’s all to the good,” said Jan Ziolkowski, the institution’s director.

When Beardsley asked to initiate the installations, Ziolkowski asked himself if there was a threat to the mission to preserve the garden, “and after listening to all the fears and paranoias I had, I said, no, there really isn’t much of a risk.”

More than 20,000 visitors a year come to enjoy the serene garden, many of them Washington regulars. Numbers have jumped in the past five years, in part because of the outdoor artworks but also because the museum was reopened after a renovation. Ziolkowski thinks the recession may have also raised attendance as people have come to nourish their souls.

Trim, lithe and a youthful 60, Beardsley has spent a career mostly in Washington as a curator, writer and academic in an area of study that embraces environmental art, land art, and landscape design and history. He teaches at Harvard one day a week. He must also attend to the traditional duties of his position: organizing an annual symposium, directing publications, and selecting and guiding interns and fellows.

He grew up in suburban New York — his father made a living in real estate before turning full time to painting and art restoration. Beardsley worked at the Hirshhorn Museum in the 1970s and at the Corcoran Gallery of Art in the 1980s and later received a PhD from the University of Virginia.

He said that as a student of art history, he was drawn to landscape as a subject because it was “suddenly everywhere” after a century of neglect. In the 19th century, it inspired painters and early photographers discovering America’s natural beauty. In the 1970s, it was embraced by a new generation of avant-garde environmental and conceptual artists.

And because much of the subjects were in the Southwest or West, it became a way for a kid from the East Coast to discover the rest of America.

Later, in an e-mail, Beardsley wrote to say that there was another formative experience that drew him to this esoteric subject of land as art. In the 1960s, his parents moved to Britain, and he found himself in an international high school in South Wales. Ancient watchtowers, medieval castles and jousting fields became part of his teenage world. In such a historically layered setting, “you absorb an awareness of cultural landscapes of so many kinds.”

Neither bombastic nor polemical, Beardsley nevertheless is still driven to open our eyes.

“If I’m fighting against anything, it’s the tendency to see the garden as a passive place without ideas,” he said.