Bannochie was born in Grenada in 1914 and, apart from her early childhood, lived all her life in Barbados. She married John Mackie Bannochie on 13 April 1964. She was a founding member of the Barbados National Trust.
With her second husband, John, she created and owned Andromeda Gardens, a scenic park with flowering plants and tropical trees in the village of Bathsheba, Saint Joseph in Barbados. Bannochie founded the garden around 1954 on 8 acres (32,000 m2) of land that had been in her family since 1740. On Bannochie's death, Andromeda Gardens was left to the Barbados National Trust.
In 1977, she was awarded the Veitch Memorial Medal by the Royal Horticultural Society for her contribution to tropical horticulture. Bannochie suffered a stroke in the summer of 1988 and died shortly afterwards. She was 73 years old.
- Leach, John (April 2004). "Tourism For Survival". Roots. 1 (1). Retrieved 2008-03-10.
- Bannochie, Iris; Marilyn Light (1993). Gardening in the Caribbean. Macmillan. ISBN 0-333-56573-8.
- Deitz, Paula (1991-02-17). "A Rare Garden in Barbados". The New York Times.
- "Heliconia Photos". 2004-04-29. Retrieved 2008-03-10.