Georgina Burne McKellar was born at Battersea, London, England, on 27 May 1832, the second daughter of Annette Clarke and her husband, Dugald McKellar, a doctor. When Georgina was about 10 years old the family moved to Madeira for the benefit of her father's health. After his death, Annette McKellar and her 10 children decided to emigrate to New Zealand. With their two servants the McKellars sailed from Madeira aboard the St Michael in August 1852, and arrived at New Plymouth on 2 December. They settled at Omata, near New Plymouth, on about 50 acres of land which they named Fernlea.
On 2 June 1856, at Omata Church, Georgina McKellar married an Omata settler, Charles Hetley. Tragically, Charles suffered a haemorrhage and died on 24 May 1857, leaving Georgina with a seven-week-old son, Charles Frederic. She sold their farm, Brookwood, probably in 1859, and returned to Fernlea with her baby. When hostilities broke out in Taranaki in March 1860 Annette McKellar and her daughters moved to New Plymouth. Their Omata home was burnt, crops destroyed and livestock carried off. Despite this experience, Georgina Hetley later wrote nostalgically of Taranaki, and her description of the view from the Pouakai Range expresses the love for New Zealand's native flora which inspired the paintings and drawings for which she is known: 'The town of New Plymouth lay far away in the distance, but we could not see it, it was hidden by the smoke of the burning "bush." The beautiful forest with its flowers and ferns is fast disappearing before the tide of cultivation, and many will only be known by their dried and shrivelled up remains.'
During her time in Taranaki Georgina Hetley made pencil sketches of Fernlea and Brookwood, and of New Plymouth during the hostilities. She also painted watercolours of scenes in Waikato and Auckland. By March 1863 she had left Taranaki with her son, and by 1879 was living in Auckland. That year she first exhibited with the Auckland Society of Artists. As a working member of the renamed Auckland Society of Arts she won prizes in 1883 for an original design for embroidered drapery and a study of foliage. She joined the New Zealand Art Students' Association, which was founded in Auckland in 1883 'with a view to developing an Art distinctive of New Zealand.' As a senior student of the association Hetley won prizes in 1884 and 1885 for her studies of wild flowers. In 1885 her paintings of indigenous flora took first prize at the New Zealand Industrial Exhibition in Wellington. She made many drawings of ferns, and from her own collection made up sets of pressed ferns for sale to augment the funds of the Melanesian mission.
Georgina Hetley is best remembered for her book The native flowers of New Zealand, which was published in London in three parts in 1887–88 and as a single volume in 1888. In the preface she described how the project stemmed from a lecture given in 1881 by the curator of the Auckland Museum, Thomas Cheeseman, describing a botanising excursion in Nelson. With the encouragement of Cheeseman, Thomas Kirk, John Buchanan and other botanists, Hetley set out 'to do for the flora of New Zealand what Dr Buller has done for its birds.'
She was granted government support in the form of free rail travel and a commitment to purchase copies of her book for public schools and libraries. The Union Steam Ship Company of New Zealand gave her free passage on its steamers. She made 125 paintings of flowers in the North Island before heading south in January 1886 to Nelson and Greymouth, and to Arthur's Pass and the Otira Gorge where she collected alpine plants. She spent six weeks in Christchurch painting the flowers she had collected, and others from Stewart Island and the Chatham Islands growing in the Government Domain in Christchurch. Despite the rigours of travel, the project 'was a labour of love. Every new flower was a delight and wonder'.
Georgina Hetley left for England in June 1886 to find a publisher for her work, prompted by the knowledge that Sarah and Edward Featon were preparing their book The art album of New Zealand flora for publication in New Zealand. While she was in London that year examples of her watercolour drawings were exhibited at the Colonial and Indian Exhibition. On the recommendation of Cheeseman, J. D. Hooker invited her to work at the Royal Botanic Gardens at Kew. There she wrote descriptions, made dissections and improved her botanical drawing skills. This experience enabled her to include in The native flowers three pages of sketches of flowers, and floral dissections of most of the 45 species reproduced on the 36 colour plates.
Hetley had aimed to produce 'a good popular' work rather than exact botanical drawings. Her success can be measured by a reviewer's comment that the plates brought 'home to us, as never before, the gorgeousness of the New Zealand flora.' The plates were purchased for a French version, Fleurs sauvages et boix précieux de la Nouvelle-Zélande, which was published in Paris in 1889.
Unable to cope with the rigours of the English climate, Hetley spent some time in Madeira. In September 1889 she returned to London before leaving for New Zealand, stopping off at Genoa and Sydney. Her proposal that she be commissioned to make botanical drawings in New Zealand for the Royal Botanic Gardens was not taken up by Hooker's successor, Thistleton Dyer. But she left England hoping to continue her work, and confident that the experience gained at Kew would enable her to make her drawings of more botanical value. Her paintings of flowers of New South Wales were placed in the Imperial Institute in London by the government of New South Wales. In 1893, in the hope that the New Zealand government might follow suit, her New Zealand flora were exhibited at the General Assembly Library in Wellington. Another exhibition of paintings of 150 specimens, including those done in Madeira and New South Wales, was held at the Auckland Museum, 'in order to make the rarer native flowers more familiar to the public.'
Georgina Hetley died at Auckland, after a long illness, on 29 August 1898. She is remembered as a forceful personality, singleminded in the pursuit of her goal to paint New Zealand's indigenous flora before it was destroyed by the advance of cultivation.