No one likes to get caught in traffic – unless it’s on the Park Avenue malls, those narrow strips of grass and flowers that separate the uptown and downtown lanes.

It’s worth crossing on a yellow to get trapped in the median and admire the cherry blossoms, the pristine tulips, and the begonias. When it turns cold, Christmas trees transform the islands into winter wonderlands.

The plantings owe their existence to the Fund for Park Avenue, which celebrated its 25th anniversary Thursday with a reception at a private club on Park Avenue. Arrangements of white and pink begonias and red and yellow Gerber daisies transformed the club’s interior – bringing the malls inside. The organizers also brought in large green lattices, which went quite well with the club’s English furniture and hunting paintings.

Park Avenue is an iconic New York street, so the event merited support from Mayor Bloomberg.

The borough commissioner for the Department of Parks & Recreation, William Castro, read the mayor’s proclamation, which hailed the “proactive property owners” whose work starting 25 years ago “would ultimately revive the avenue.”

The proclamation also tallied up the number of flowers that have been planted: 2.1 million tulips, 750,000 begonias, and 600 trees. The color of the tulips changes annually and is decided upon by the fund’s executive director, Margaret Ternes. (Next year’s will be pink.)

It isn’t easy to plant all that. But Peter van de Wetering has done so since the fund’s inception, tackling the “terrible drainage” and flowerbeds that are only 2 feet deep. Not to mention how unnerving it can be to be planting on a narrow strip with cars whizzing by. Mr. Van de Wetering orders the tulips from Holland and grows the begonias on his farm in Long Island.

The annual bill for flowers and planting comes to $800,000, which the fund raises through contributions from more than 100 Park Avenue buildings. The owners give a dollar amount based on the number of units in their buildings. The fund works with the buildings between 54th and 86th streets, while the Carnegie Hill Neighbors solicits from buildings between 86th and 96th.

At first, participation wasn’t easy. Ms. Ternes recalled the reaction of the president of 550 Park Ave.: “I’ll have to check with my managing agent and make sure this isn’t some scam out of Texas.”

Once 550 was signed on, others followed.

The project has evolved over the years. “When we first started, we would get 50 checks from the individuals living in a building,” the chairman of the fund since its inception, Ronald Spencer, said. “Now the buildings write us one check.”

Still, money is money, and even on Park Avenue it doesn’t grow on trees.

“It’s not mandatory to contribute, but the pressure can be great,” the president of 1235 Park Ave., Jessica Leeds, said. Ms. Leeds, who described her building as “pretty stodgy,” was one of several building presidents at the reception.

Guests spoke proudly and protectively of the malls, which they refer to as their front and back yards.

“I’ve walked up and down the street for 50 years,” James McCollom said. “It makes me mad when I see people walking their dog on the mall – but that doesn’t happen much anymore.”

Residents of Park Avenue tend to stick around for a while. Judy Steckler, for instance, has spent more than 50 years at 863 Park Ave. The only time in her life she didn’t live there was during her 10-year marriage.

And the Fund for Park Avenue has devised a way for residents like Ms. Steckler to remain a part of Park Avenue even after death. The fund’s brochure on bequests reads: “There are a number of ways to assure that your name is linked with Park Avenue in perpetuity.” Bequests can be marked by a plaque in the flowerbeds.

For the winter evergreens, which cost $300,000 annually, the fund solicits individual contributions from Park Avenue residents and neighbors, who live “as far away as Fifth Avenue,” a board member of the fund, Mary Davidson, said.

John Bradley, who lives on the West Side, has supplied many of the trees from his forest preserve in upstate New York. Two of his trees, both more than 200 years old, are on the list for the Christmas tree at Rockefeller Center.

In addition to flowers and trees, the fund advises on public art for the avenue. About four years ago, the fund founded a committee that makes recommendations to the city on public art installations on the mall between 52nd and 53rd streets – a desirable spot to artists because of its location in front of the Seagram Building, designed by Mies van der Rohe.

The members of the committee are a former director of the Metropolitan Museum of Art, Richard Oldenburg; the art dealer Andre Emmerich; the chairman of the Pollock-Krasner Foundation, Charles Bergman; a former director of the Frick Collection, Samuel Sachs II, and the director of the Montclair Art Museum, Patterson Sims. Work by Beverly Pepper will be on display until August. The next sculptor is Deborah Butterfield.

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Dorothy and Lewis Cullman have their names on several programs and buildings in New York City, assuring their generosity will be remembered. They also make numerous gifts more ephemeral in nature, such as their financing of the Lincoln Center Out of Doors festival.

The festival began in 1971 under the direction of the Lincoln Center’s director of community relations, Leonard de Paur. In 35 summers, it has grown into one of the largest and oldest free festivals in America, offering music, dance, theater, and public art.

The Cullmans joined de Paur’s widow, Norma, at a luncheon Wednesday to preview this year’s festival, which runs from August 13 to September 4.

“What it’s really about is this great use of space,” Mrs. de Paur said. Events take place in Damrosch Park; the South Plaza, behind the New York State Theater; the North Plaza, north of the Metropolitan Opera House, and the Josie Robertson Plaza, at Columbus Avenue and 64th Street.

Highlights include an International Hip-Hop Exchange, a homemade instrument day, and a two-day showcase of country-and-western artists. The Paul Taylor Dance Company and the Stephen Petronio Company will perform. For children, there’s a puppet pageant telling the story of Moby Dick and clowns from the Big Apple Circus.