Mellon, daughter of Gerard Barnes Lambert, president of the Gillette Safety Razor Co. and granddaughter of Jordan Lambert, who founded Lambert Pharmaceuticals and invented Listerine, died Monday, Forger said.
The heiress was known for her horticulture skills, which were self-taught. Mellon designed her first garden at the age of 23 for fashion designer Hattie Carnegie. She was paid for that job with a coat and dress.
She went on to design gardens for dozens of clients, donating her payments to horticulture or medical causes.
Most of her life was lived privately, but Mellon became well known for her gardening after former first lady Jacqueline Kennedy asked her to redesign the White House Rose Garden. Kennedy then commissioned Mellon to design the White House East Garden, which was completed after former President Lyndon B. Johnson entered office.
Mellon received a Conservation Service Award in 1966.
"The nation will be ever indebted to you for your gift of talent to the design and development of the Rose Garden and the Jacqueline Kennedy Garden at the White House," former Interior Secretary Stewart L. Udall said when presenting Mellon with the award.
Mellon is survived by sons Stacy Barcroft Lloyd III and Timothy Mellon, daughter Catherine Conover Mellon, two grandchildren and two great-grandchildren.