Silvana Caterina Kerstich was born in Zadar, Dalmatia, subsequently Yugoslavia, on 9 February 1942. She was educated in Italy and completed her education in Brisbane after she migrated with her parents as refugees to Australia in 1951. She graduated in fine arts and literature from the University of Queensland. Gardner went on to work as a visual artist and to write poetry. Her visual works are represented in major collections in Australia, Canada, and America, including the American Telephone & Telegraph collection, New York; National Gallery of Victoria; Queensland Art Gallery; and Griffith University collection. Gardner has been involved with literary workshops, poetry readings, youth festivals, and writing workshops in schools and with underprivileged youth.