She is best known for her novel, Annie on My Mind (1982), which was critically acclaimed but attracted controversy because of its lesbian characters, Annie and Liza who fall in love. It was one of the first teen novels to feature lesbian characters in a positive light. In 1993, it was banned by the Kansas City school system and burnt in demonstrations. It was returned to shelves only after a First Amendment lawsuit by students in 1995. It is #48 on the American Library Association's list of 100 Most Frequently Banned or Challenged Books, 1990-2000.

Garden earned a B.F.A. (1961) and an M.A. (1962) from Columbia University School of Dramatic Arts. Through school and for several years after college, Garden worked in theater, supplementing the work with odd jobs in offices. She later taught school and worked as an editor of children's literature. She has also written non-fiction, mystery and fantasy for children and young adults. Other titles also feature GLBT characters. In 2001, Garden received the Robert B. Downs Award for Intellectual Freedom from the University of Illinois' Graduate School of Library and Information Science. In 2003, the American Library Association awarded her the Margaret A. Edwards Award for lifetime achievement in writing books for teens.

Garden's review of young adult titles have appeared in the [[Lambda Literary Foundation]]'s Lambda Book Report.

She currently divides her time between Massachusetts and Maine, with partner Sandy Scott, their golden retriever, Loki, and their cats.

Works are listed by publication date.

Fiction

• What Happened in Marston (1971)
• The Loners (1972)
• Mist Maiden (1975)
• Annie on My Mind (1982)
• Maria's Mountain (1983)
• Prisoner of Vampires (1984)
• Peace, O River (1986)
• Lark in the Morning (1991)
• My Sister, the Vampire (1992)
• Dove and Sword: A Novel of Joan of Arc (1995)
• My Brother, the Werewolf (1995)
• Good Moon Rising (1996)
• The Year They Burned the Books (1999)
• Holly's Secret (2000)
• Prisoners of Vampires (2001)
• The Case of the Stolen Scarab (2002)
• Nora and Liz (2002)
• Meeting Melanie (2002)
• Molly's Family (2004)
• Endgame (2006)
• Hear Us Out! (2007)

Weird and Horrible

• Vampires (1973)
• Werewolves (1973
• Witches (1975)
• Devils and Demons

Fours Crossing

• Fours Crossing (1981)
• Watersmeet (1983)
• The Door Between (1987)

Non-Fiction

• The Kids' Code and Cipher Book (1988)