Like her husband, Arthur, Ninah Cummer was active in civic and charitable organizations. She distinguished herself quite early in Jacksonville by organizing relief after the city’s staggering fire of 1901 and as a Red Cross volunteer during World War I. In 1910 she was elected president of the Women’s Advisory Board of the Children’s Home Society of Florida, a position she held until 1940. In addition, she served as treasurer of the Woman’s Club for two years, followed by two years as president.
She organized the first Garden Club of Jacksonville in 1922 and was the first president of the City Federation of Jacksonville Garden Clubs, later extending her scope to include all of Florida. She was also elected, in absentia, president of the Garden Clubs of America, but declined the honor.
During the Depression, Mrs. Cummer was active in the Mobilization for Human Needs, a charitable program to bring food and supplies to the needy. She often gave lectures around the state on gardening and caring for the needy, and, at one point, had her own radio program to discuss these special interests.
