The longtime Roland Park resident was 76.
"She would always say she was a professional volunteer," said her husband, Dr. John H. Sadler. "She was always doing things," he said.
Born Joan Brown in Atlanta, she was the second of three children. Her father was a diesel mechanic and heavy equipment technician, and her mother was a homemaker. Part of Mrs. Sadler's childhood was spent in Baton Rouge, La., before the family moved to her parents' native South Carolina.
In 1953, she graduated from Honea Path High School, where she met her future husband. Dr. Sadler said he noticed her in the hall at school but they did not talk until they worked together on the school play their junior year. "We thought it might be nice to go out, and we never stopped," he said.
After high school, Mrs. Sadler attended the Presbyterian Hospital School of Nursing in Charlotte, N.C.. while Mr. Sadler attended Duke University. The day after she graduated in 1956, they got married. Mrs. Sadler then supported the couple while her husband attended medical school at Duke.
"She was earning a living that got me through medical school," he said. "I've been able to do a lot of things because of her."
They had two children while he was finishing school. Shortly thereafter, the family moved to Atlanta, where Dr. Sadler completed his residency and Mrs. Sadler later left nursing to work as a teacher's aide so she could spend more time with their daughter and son.
While in Atlanta, the couple had season tickets to the Atlanta Symphony Orchestra and she began to volunteer, helping to organize the decorator's show house fundraiser each year, among other activities with the organization.
In 1963, the family moved to Wichita Falls, Texas, where Dr. Sadler was stationed at Sheppard Air Force Base. Mrs. Sadler worked for the Red Cross as a phlebotomist, traveling around Texas and Oklahoma.
Two years later, the family returned to Atlanta, where Dr. Sadler was a faculty member of Emory University and Mrs. Sadler continued her work with the symphony and began taking horticulture classes.
She used her skills from working with the Atlanta Symphony when the family relocated to Baltimore in 1972, when Dr. Sadler was named the head of nephrology at the University of Maryland.
"She taught herself a lot of things. If she wanted to do something, she learned about it and did it," said Mrs. Sadler's daughter, Patricia Stephenson.
As a volunteer, Mrs. Sadler began doing odd jobs, such as stuffing enveloprs, but she helped start the Baltimore Symphony Decorator's Show House fundraisers and became the organization's first chairwoman. She later served as the president of the Baltimore Symphony Associates volunteer organization.
"She did not want to be a member of the doctors' wives. She wanted her own identity," Mrs. Stephenson said. "She had a great independent spirit about her," she said.
At the symphony, she said, her father became known as "Mr. Joan Sadler."
Mrs. Sadler also became active in the Catonsville Garden Club where she held several offices, including club president. She represented the national Garden Club of America on the horticulture and program committees. She became a master gardener in 1999 after completing a program at the University of Maryland.
"Joan never thought of herself as anything special. She was so much more talented than she gave herself credit for," Dr. Sadler said, recalling all the garden projects she helped design. He said people would often ask her for guidance in landscape design.
In 2001, she received the Garden Club of America Horticulture Award and the Zone Civic Improvement Award in 2008.
Mrs. Sadler also routinely volunteered at Cylburn Arboretum and helped design several urban gardens around Baltimore, as well as the knot garden at the Catonsville Historical Society.
Her home garden was small but impressive, with several paths running through it. She had a knack for always having a different type of azalea in bloom. Among her favorite plants were her oak leaf hydrangeas.
She would always offer up some spare plants in buckets to anyone, saying "I thought you could use this over here," her daughter recalled. And to tote her bucketed plants or sacks of mulch to various projects, she drove a Toyota truck.
"She loved that truck," Mrs. Stephenson said, adding that the only other thing she wanted was a Bobcat backhoe. And when she would prepare to head out to another project, Dr. Sadler joked that she prepared as though "she was prepping for an invasion."
Mrs. Stephenson said her mother never stopped working, adding that one of Mrs. Sadler's grandchildren said, "She may have been 76, but she was not an on-the-porch old lady."
In addition to her husband of 54 years and her daughter, Mrs. Sadler is survived by her son, John M. Sadler of Roland Park; her brother, O.C. Brown III of Jacksonville, Fla.; her sister, Betty Young of Chester, S.C.; and five grandchildren.
A celebration of her life was held on Friday at Ruck Funeral Home in Towson. Memorial contributions may be made to the Cylburn Arboretum.