Gwendolen G. Edwards attended the Wynberg High School for Girls in Cape Town, but matriculated at the Good Hope Seminary in 1906. She was already interested in botany while still at school and at the age of sixteen won a competition for a collection of pressed flowers. As a result she came into contact with Dr Harry Bolus* and subsequently befriended his niece, Miss H.M.L. Kensit (later Dr H.M.L. Bolus*). During 1907 and 1908 she passed two teacher's examinations and in 1908 also studied botany under Mr W.T. Saxton* of the South African College. In 1909 she was appointed to a teaching post at Porterville, Western Cape, where she taught botany, English and history in Grades 9 to 12 until the end of 1912.
In 1913 Edwards continued her studies at the South African College, obtaining the Bachelor of Arts (BA) degree of the University of the Cape of Good Hope in 1916, with major subjects botany, geology and chemistry. The next year she was appointed science mistress at the Roedean School for Girls in Johannesburg, where she was also put in charge of the newly established garden for indigenous plants on the school grounds. The garden was later named after her. During her 31 years at the school she corresponded and exchanged specimens with the director of the National Botanic Gardens at Kirstenbosch and other botanists. She found several new species of plants that were named after her by Dr H.M.L. Bolus, namely Conophytum edwardsiae, Delospermum edwardsiae, Drosanthemum edwardsiae, and Lampranthus edwardsiae. Around 1929 she drew the attention of Professor C.E. Moss of the University of the Witwatersrand to naturally occurring hybrids between two species of Clematis growing near Johannesburg and he proposed to name them after her. Some drawings of plants made by her were preserved at the Bolus Herbarium. During the nineteen-forties she and others persuaded the city council of Johannesburg to establish "The Wilds" indigenous garden. After her retirement in 1948 she became the first guide-lecturer there, until ill health forced her to give it up after two years.
In 1946 Edwards was one of a small group of people who established the Arboricultural Society of South Africa (later the Tree Society of South Africa). She actively participated in its activities for some years and contributed articles to the journal Trees in South Africa. Just before her death she was elected an honorary life member of the society.