Barbara Cook performs at the Segerstrom Center for the Arts on Saturday. (Denise Winters / April 11, 2013)

Broadway luminary Barbara Cook is in for a treat.

During her one-night-only performance at the Renée and Henry Segerstrom Concert Hall on Saturday, she will be presented with a birthday card.

Yes, birthday cards are common, but not ones filled with best wishes submitted by fans nationwide.

Since Saturday's performance is to celebrate the year of Cook's 85th birthday, the Segerstrom Center for the Arts created a way for fans to wish her well via Twitter and Facebook. (Her actual birthday is Oct. 25.)

"Getting old is about loss — all different kinds of loss — and you have to deal with that constantly," said Cook, a New York resident. "That's not always easy, but I'm so grateful to still be breathing and singing."

After the 8 p.m. concert, Cook will remain on stage to chat with ASCAP Director of Musical Theatre Michael A. Kerker and answer audience queries, which have been submitted via social media.

"Questions received so far range from what is her most memorable moment onstage to how it feels creating a role such as Marian the Librarian [in "The Music Man"] to who in her career has been an inspiration to her — as she has [been] to so many artists," said Terrence W. Dwyer, the center's president.

The Segerstrom Center has previously conducted such a conversation with Stephen Sondheim. Similar events known as Talk Backs are also hosted during Broadway runs, allowing guests to engage with cast and company members.

Cook proposed the question-and-answer portion for her own show, Dwyer said.

Music plays a dual role in the soprano's life by filling her days with a beloved activity while also allowing her to "pay the rent."

"I think most people like to sing, and most people who don't sing well would love to be able to sing well," Cook said. "It's a great way to communicate with people, and I enjoy it enormously."

Cook grew fascinated with singing when she was a young girl. She was only 8 years old when she was first paid to perform — in Atlanta, her hometown.

"It was at a movie house near where I lived," she recalled. "I did a little tap, and they paid me 50 cents."

Cook moved to the Big Apple in 1948 and launched her Broadway career three years later with the lead role in "Flahooley." Over the years, she starred in "Oklahoma!" "Candide," "The Music Man," "The King and I" and "Showboat" and also recorded eight original cast albums.

Now she spends less time training and focuses mostly on piecing together each performance. An hour-long concert typically includes about 15 songs, while a 90-minute show, like the one at Segerstrom, features between 21 and 25 songs.

The process begins with Cook perusing her trusted list of songs, looking for numbers that the audience, and she, will enjoy.

"Putting an act together is not easy," she said. "Choosing a beginner and closer and slowly filling the time in between is very time-consuming."

Influenced by Mabel Mercer, an English-born cabaret singer, and her singing coach, Robert Kobin, Cook says that while she cannot whittle down her list to a favorite song, she always enjoys performing "He Was Too Good To Me," by Richard Rodgers and Lorenz Hart.

"That's a beauty — one that I particularly like," she said.

Cook, who joined Vanessa Williams and Tom Wopat in the Roundabout Theatre Co.'s production of "Sondheim on Sondheim" in 2010, has received Tony, Grammy, Drama Desk and New York Drama Critics Circle awards. She was also nominated for two Olivier Awards and inducted into the Theater Hall of Fame.