The new National China Garden in Washington will follow classic design principles of nature represented by ponds and stones. (International Center for Bamboo and Rattan)

Like a Chinese garden of stone and water, international relations are a careful balance of the hard and the soft.

Practicing the softest of diplomatic wooing, senior Chinese officials and their American counterparts gathered in a bright, wind-swept meadow at the U.S. National Arboretum on Friday to mark the creation of one of the largest Chinese gardens to be built on North American soil.

When it is completed — supporters anticipate in three years — the 12-acre, $120 million confection of pavilions, gateways, water features and walled enclosures will bring a taste of the great, dynastic pleasure gardens of old China to Northeast Washington.

The Chinese will be bankrolling most of the National China Garden at the 446-acre arboretum between New York Avenue and the Anacostia River. Congress agreed to donate the site in 2008. For the arboretum — a research and display garden run by the Agriculture Department — the China garden represents probably the most valuable single addition in the institution’s 89-year history, Director Richard T. Olsen said. It also offers a shot in the arm to a botanical mecca that has been underfunded for years.

First proposed in 2004 as a jointly funded Sino-U.S. project, the project limped along in the inimitable Washington way. But it was revived with the 2011 creation of the National China Garden Foundation and the decision by the Chinese government to provide most of the funds. Of the total cost, $30 million will be used to endow the garden’s maintenance and programming. The timetable for Friday’s groundbreaking was part of the summit agreement between President Obama and Chinese President Xi Jinping when they met in September.

The China Garden will occupy 12 acres in the heart of the U.S. National Arboretum and include a series of elevated pavilions for gathering and viewing. (National China Garden Foundation)

China has helped establish other Chinese gardens in Europe and North America, including in Portland, Ore., Pasadena, Calif., and Vancouver, British Columbia. But the arboretum’s is the first one created directly by Washington and Beijing, said Samuel T. Mok, president of the foundation.

Its scale is also unusual. Using principles of feng shui, the garden will incorporate aspects of famous classical gardens in various Chinese cultural centers, including the bamboo-rich Geyuan Garden, built during the Qing Dynasty, and other gardens in Yangzhou.

The finished garden will include a peony garden, a scenic lake, gardens of ornate stone and a grand pavilion, to be fabricated by Chinese artisans.

In the bucolic heart of the arboretum, dignitaries gathered on a red, cloth-draped dais as the national flags of China and the United States flapped in the afternoon breeze. The recurring theme of their speeches was of the garden’s symbolic cultural importance. “I hope our cooperation will be as enduring as this garden will be,” said Catherine A. Novelli, an undersecretary at the State Department.

The garden and its structures will be used for “robust” cultural programs between Chinese and U.S. organizations, the officials said. Chinese Ambassador Cui Tiankai, in an interview, said the garden will be “important for the people of our two countries, not only for the governments.”

Catherine Woteki, the Agriculture Department’s chief scientist, said the garden “is going to provide opportunities for research as well as something to be enjoyed by the public.” She said the department recently signed an agreement with China on research using the animal and plant gene banks that each nation preserves. The two countries have the largest gene banks for agriculture in the world, she said.

For the arboretum, the garden will provide a hub to connect the institution’s disparate collections of Chinese plants, said Olson, the director, referring to its inventories of Chinese magnolias, crape myrtles and conifers. “And we get to plant so much more. It’s something long overdue and a unifying theme for the arboretum.”

So as the National Zoo’s Bao Bao returns to China, Washington loses a panda but welcomes a garden.