Zara Katznelson was born in Winnipeg to the family of a professional musician, Gregor Katznelson, who was a flutist performing under the name Nelsov. Zara's performing name is the Russian feminine form of her father's stage name. The family had emigrated to Canada in 1910.
She said she would like to play cello as early as four and a half years old. Her father got a viola converted to hold in gamba position like a cello and gave her lessons. She recalled that his lessons technically prepared her, as well as teach her discipline and how to practice.
And she did well: When she was five years old, her family formed the Canadian Trio with her two older sisters who played violin and piano. At the age of six, she was sent to study with cello teacher Dezso Mahalek. When she was 11, she entered a talent competition. One of the adjudicators was Sir Hugh Roberton, who advised that Zara and her sisters be taken to London to complete their musical education. The family took the advice and relocated in 1930. At that point, the family Anglicized its name to "Nelson."
She became a pupil of Herbert Walenn at the London Violoncello school. She studied with him for six years and gained very secure technical training and the start of her repertoire. Early in her studies with Walenn, she made her debut at a charity concert of the Royal College of Music, wich led to an engagement with Malcolm Sargent and the London Symphony Orchestra performing Lalo's cello concerto.
She held off making a formal solo recital debut until she was 17 (Wigmore Hall, 1936). The conductor and former cello player Sir John Barbirolli was impressed with her playing and gave her considerable musical advice. She attributed the development of her sound -- a narrow, very singing tone -- to Barbirolli's suggestions. He took her to play for Casals, who predicted a successful solo career. Casals at the time did not teach, but when he started teaching about ten years later, the now 29-year-old musician went to study with him in Prades, spending two seasons polishing her technique. She also had short periods of study with Feuermann and Piatigorsky.
The family moved back to North America at the outbreak of World War II in 1939, settling in New York. She did not make a debut recital there until 1942, at Town Hall. The critics gave her the highest praise and her career was finally launched in a decisive way. It has been a brilliant one, as predicted by Casals. She was the first American soloist to tour the Soviet Union, playing the Kodály and Rachmaninov sonatas. The audience greeted her performances rapturously and like a long-absent returning daughter.
She has been a strong supporter of twentieth century repertoire. She gave the British premieres of the Shostakovich and Hindemith sonatas and the Samuel Barber cello concerto, which she had learned in three weeks for the occasion. After that, she recorded the concerto under the baton of the composer. After the sessions, one of the cellists of the orchestra leapt to his feet, brandishing the instrument, and screamed that he could never play again after hearing her. At that, he smashed the cello against the wall to the cheers of his colleagues. It dawned on Nelsova that the orchestra had gotten a cheap cello with which to make this gesture, but also was a true expression of their admiration. She also recorded Ernest Bloch's Schelomo under its composer's baton, as well as his Prayer, Supplication Jewish Song.
She embarked on a teaching career at New York's Juilliard School and the College-Conservatory of Music in Cincinnati and gives master classes. Her teaching is directed to working not so much on technical matters like fingering and bowings, but to concentrate on emotion and intellectual involvement in the music. She plays the 1726 Marquis de Corberon cello of 1726, a beautiful instrument loaned to her by Audrey Melville of London.