The youngest of three children to parents hailing from Dumfries, she was encouraged by her mother to paint from an early age but preferred watercolour over oil.
Grierson served in the Women's Auxiliary Air Force as a flight officer in a photographic reconnaissance unit and used the skills she learnt into use later in her life.
[3] She spent 1931 teaching English to a German family but returned home to study at Battersea Polytechnic and found employment as a confectioner in Llandudno.
[3] When World War II broke out,[4] Grierson served in the Women's Auxiliary Air Force as a flight officer in a photographic reconnaissance unit,[5] and was based at Medmenham in Buckinghamshire.
[4] Hunting Aerosurveys sent Grierson on a week's course in pen and ink drawing at the Flatford Mill Field Centre in Suffolk ten years later.
[4] In 1966, she won her first gold medal for flower painting from the Royal Horticultural Society (RHS),[6] and was invited to contribute designs for two postage stamps for the Post Office the next year: a primrose for the 9d and a violet for the 1s.9d.
In 1975, her paintings were put on display at the Hunt Institute for Botanical Documentation in Pittsburgh, and she illustrated her second book that same year, Trees and Shrubs of the British Isles by William Bean.
[4] Her work was further exhibited at the Pacific Tropical Botanical Garden in 1984 and received an honorary Master of Philosophy degree from the University of Reading two years later.
Grierson illustrated Brian Mathew's Hellebores in 1989 and earned a silver medal at the 1990 International Book Art Exhibition in Leipzig.
[1] Grierson's work in Hawaii appeared in Peter Shaw Green's A Hawaiian florilegium: botanical portraits from paradise in 1996 and was awarded the Victoria Medal of Honour by the RHS in 1997.