Zimmermann is known for her love of the color purple: she favors purple clothing, decorates her house in a purple scheme, and even has a purple car.
Zimmermann was born in 1887. In 1898, at the age of twelve, she attended her older sister Anna's wedding in Stonebridge, Pennsylvania, where she met Hilda Weiss "Granny" Wetherbee, who detected the spark of magic within her and showed her how to find her own powers and use them. She crafted a special crystal, which was linked to Florence and then buried in the earth for at least seven years; when Florence eventually laid hands on it for the first time, she used it as a part of the umbrella she would use for a magic wand, which helped focus her powers.
In 1905, while visiting her cousin Oley Gunderson in Petoskey, Michigan, she fought with another girl named Gert Bigger over a boy named Mordecai Hunks, winning the fight and briefly dating him. However, they broke up by the end of the summer.
Florence later traveled in Europe in 1913, where she met the painters Henri Matisse and Claude Monet, receiving a painting from each of them. Matisse's painting, of a room where almost everything was purple, would later hang in one of the guest rooms of her home in New Zebedee; Monet's painting of purple water lilies would hang in another guest room in the same house.
By 1922, Florence was married to Honus Zimmermann, and was a member of the Capharnaum County Magician's Society. That same year, at the age of 35, she earned her Doctorate of Magical Arts from the University of Göttingen in Germany. Her dissertation was titled A Free Inquiry into the Properties of Magic Amulets, which she later had published. After getting her degree, she and Honus returned to America that same year. The exact dates of their wedding and his death are not given in the books, but according to notes made by Bellairs (in preparation for writing The Ghost in the Mirror), as relayed by Brad Strickland, they were married before she went to Europe, and she found work as a schoolteacher after he passed away.
In 1943, Florence's best friend, Jonathan, bought the home of the late warlock Isaac Izard, who had lived next door to Florence for years, and tore down the fence between their homes. Five years later, in the summer of 1948, a recently retired Florence met Jonathan's nephew Lewis when he moved in. In April of 1949, she participated in the battle against Isaac's wife Selenna, who had returned from the dead. Soon after, she met Lewis's new friend, Rose Rita Pottinger, whom she formed a close, motherly and/or sisterly friendship with.
In December of 1949 (during the events of The Figure in the Shadows), Florence battled the evil spirit of Eliphaz Moss, who was trying to lure Lewis to his death. Unfortunately, she was defeated, and the crystal in her umbrella/wand was destroyed, thus robbing her of much of her magical powers. Jonathan did give her a new umbrella for Christmas, but she was unable to use it as a wand at the time.
The following summer, in preparation for her trip to her late cousin Oley's farm, Florence bought a purple 1950 Cranbrook Plymouth, but was rather annoyed when a bright green one was delivered instead. She kept the car anyway, which Rose Rita would later name Bessie during their trip. Also during the trip, they encountered Florence's old rival Gert Bigger, who nearly killed both of them with magic before being turned into a tree by the demon Asmodai.
In the summer of 1951, nearly eighteen months after losing much of her magic, Florence (now 64) and Rose Rita traveled to Stonebridge, Pennsylvania, only to wind up traveling back in time to February of 1828, where they met the young Hilda Weiss and her step-grandfather, Grandpa Drexel, an earth witch like Florence herself. At Rose Rita's request, he used a special crystal (of the same type as the one destroyed by Eliphaz Moss) that he had made. Like her original, the crystal was linked to Florence, and then buried in the earth. A little over a week after it was buried, Florence aided Hilda, her younger brother Heinrich, and Rose Rita in battle against the evil sorcerer Adolphus Stoltzfuss, and was, unwittingly, the cause of his defeat when she held up a mirror that reflected the one he had been using to contact the demon Aziel, who took him away. Soon after, Florence and Rose Rita returned to 1951, where Florence recovered the crystal that had been prepared for her. As it had been buried for 123 years, rather than the intended seven, her restored powers were much stronger than before. Soon afterward, Jonathan and Lewis returned from their vacation in Europe, and Florence revealed her restored powers to them by using her new umbrella, which she had modified by adding her new crystal and a griffin's talon she had bought earlier that summer, to change her car Bessie from green to purple.
Florence would go on to have other magical adventures with Rose Rita, Lewis and Jonathan, including battles with the paper golem Immanuel Vanderhelm, the witch Belle Frisson, the sorcerer Mephistopheles Moote and the half-man, half-Old One Elihu Clabbernong, the warlock Ishmael Izard (son of Isaac and Selenna Izard), and others.