Fannie Mahood Heath was born on March 5, 1864, in Wykoff, Minnesota. She was taught gardening at a young age by both her parents and grandparents. Her father, John Mahood, had learned the medicinal value of plants from Native Americans during the California gold rush of 1850. Her grandmother had also given her a small garden plot at the age of seven. The family moved to Grand Forks, Dakota Territory, in 1880. She married Frank Heath of Grand Forks on June 16, 1881. The couple homesteaded in on a farm in Brenna Township, west of the city.

Upon arriving, she decided that the farm needed protection from the wind. She first planted lilac bushes and fir saplings. The firs quickly died, but the lilac trees survived. After speaking with a florist, she learned that their farmstead was on a heavy alkaline area. He advised them to abandon the homestead and find another. The Heaths, however, had different plans. They decided to discover what plants grew well on their farm. They also tried different techniques to neutralize the soil. The most radical method used was to pour vinegar on the ground. The vinegar would react with the alkaline in the soil and bubble. She knew the soil was neutral when it stopped bubbling. She discovered later that she was the first person to use this process.

She continued to plant lilac bushes, cottonwood, box elder and willow trees to form a shelterbelt around the farmyard. She raised a son, Frank, and a daughter, Pearl. After Frank died in 1902, she told her husband that she wanted to leave North Dakota. Her husband replied that they had spent too much of their life on the homestead to leave. To cope with her sorrow, Fannie began to correspond with different people. She sent surveys of bird migrations to the Biological Survey in Washington, DC. She wrote O. A. Stevens at the North Dakota Agricultural College about the Latin nomenclature of plants, and also came to know C. B. Warden at that same institution. They both agreed that it was necessary for farmsteads to create gardens for food and beautification and shelterbelts for protection from the fierce North Dakota winds. In 1923 C. B. Warden published Perennial Flowers in North Dakota with Fannie as co-author. In 1922 Hamilton Traub asked her help in establishing a National Horticulture Society. She became vice president when the society was established in July of 1922. Besides simply corresponding with people, she also exchanged seeds with them. She collected seeds from all across America, Norway, England, and China. During her seed exchanges, she formed a special relationship with T. Hay, the superintendent of the Kew Gardens in London, England. He found it interesting that Americans would come to England to find the newest roses, delphiniums and other European flowers without even thinking that there may be more beautiful flowers in America.

One American saw the beds of flowers that T. Hay planted with Fannie's seeds and decided to purchase large quantities of the seeds without even knowing that they were American wildflowers. Fannie decided to do something about this lack of appreciation for American wildflowers. She wrote articles for Park's Floral, Nature, National Geographic and Botanist magazines on the value and beauty of growing native plants. She was asked to join the Great Plains Horticulture Society in 1925. Also, in that same year, she decided that she could no longer host the hundred-plus people who would visit the farm on weekends. In 1925, it was estimated that there were over 450 varieties of shrubs and flowers on four acres of land on the Heath farm.

She was asked to design the landscape for the Theodore Roosevelt cabin that was, at that time, on the capitol grounds in Bismarck, North Dakota. She planted 45 native shrubs, nine native trees and 150 varieties of native flowers there. She considered this one of the high points of her life. She died on September 29, 1931 at the age of 67. There was an exhibit in memory of Fannie Mahood Heath at the 1933 "Century of Progress" Exposition in Chicago. The exhibit included photographs of Fannie, her garden, and the Roosevelt Cabin. It proclaimed her as the "Flower Woman of North Dakota."