[10] At age twenty, she was introduced to one of her primary mentors, the botanist Charles Sprague Sargent, who at Harvard University was both a professor of horticulture at the Bussey Institute and the founding director of the Arnold Arboretum in Boston, Massachusetts.

[13] Farrand lived at Sargent's home, Holm Lea in Brookline, Massachusetts, in 1893 and studied landscape gardening, for which there was no specialized school at the time, botany, and land planning.

[14][15] She wanted to learn drafting to scale, elevation rendering, surveying, and engineering, and so studied at the Columbia School of Mines under the direction of Prof. William Ware.

[1] Jekyll's series of thematic gardening books emphasized the importance and value of natural plantings and were influential in the U.S.[17] On December 17, 1913, Beatrix married Max Farrand,[14]: 35  the accomplished historian at Stanford and Yale universities, and the first director of the Huntington Library.

[18] She began practicing landscape architecture in 1895, working from the upper floor of her mother's brownstone house on East Eleventh Street in New York.

[14]: 54  In 1912, she designed the walled residential garden, Bellefield, for Mr. and Mrs. Thomas Newbold in Hyde Park, New York (now a part of the Franklin D. Roosevelt National Historic Site).

[25]: 146, 195, 203–04 Farrand commuted cross-country by train for her eastern projects, such as the design and supervision of the Chinese inspired garden at 'The Eyrie' for Abby Aldrich Rockefeller in Seal Harbor, Maine (1926–35).

This was the era of the automobile, and in her designs Farrand applied principles learned earlier from Frederick Law Olmsted's drives at the Arnold Arboretum and the Biltmore Estate of George Washington Vanderbilt II.

John D. Rockefeller Jr.[26] sought out and funded Farrand to design planting plans for subtle carriage roads at Acadia National Park on Mount Desert Island, Maine, near her Reef Point home (c.1930).

[28] Henry James introduced her to Theodate Pope Riddle, "one of her most fascinating clients", who owned the estate 'Hill-Stead' (1913), now preserved as the Hill-Stead Museum in Farmington, Connecticut.

[25]: 188–89, 198–201, 209 In 2014, Farrand was recognized for her work designing the Peggy Rockefeller Rose Garden[31][32] at New York Botanical Garden, a winning site of Built by Women New York City,[33] a competition launched by the Beverly Willis Architecture Foundation during the fall of 2014 to identify outstanding and diverse sites and spaces designed, engineered and built by women.

She was the consulting landscape architect at Yale University in New Haven, Connecticut, for twenty-three years (1923–45), with projects including the Marsh Botanical Garden.

[43] After a wildfire on the island and facing a lack of funding to complete and ensure the continued operation of a center she made a remarkable decision in 1955 to discontinue the preparations, dismantle the garden, sell the property, and use the proceeds for her last years.

John D. Rockefeller Jr. purchased all Reef Point's larger plants for his Asticou Azalea Garden in Northeast Harbor, Maine, which continue to flower.