Elizabeth Anne Milne was born on 24 December 1858 in Allerum, Sweden, the daughter of Elizabeth Price, a Scotswoman, and her husband, Henry Alexander Milne, an Englishman who owned a copper mill at Virum estate, Kalmar county. Although it is thought that Elizabeth was sent to England for most of her early education, it was in Sweden that she acquired her skills in cooking and other household arts. She met English-born civil engineer Richard Gard'ner there, and they married in Gothenburg (Göteborg) on 28 September 1880. There were no children of the marriage.
At first, the couple settled in Copenhagen, but because Richard Gard'ner's career centred on railway projects they left for Tasmania, where a railroad was under construction. By 1887 they were in Greymouth, New Zealand. Gard'ner was an agent for Messrs McKeown, Robinson and Avigdor, the contractor for the New Zealand Midland Railway Company, who planned to build a railway from Canterbury to Nelson via Arthur's Pass and the West Coast. However, delays and difficulties affected the couple's financial situation and Richard's health rapidly deteriorated. Elizabeth faced the prospect of becoming the breadwinner.
In 1894 the Canterbury Women's Institute proposed a School of Domestic Instruction for Christchurch, and when it opened early in 1895 she was its superintendent. Located in Lichfield Street, Christchurch, this new school was soon attracting students. By the second term Elizabeth Gard'ner had 120 enrolled for her day and evening classes in cooking, laundry-work, dressmaking and needlework. Although classes were primarily for women and girls, 'to thoroughly prepare their daughters or themselves for household duties, as misstresses [ sic ] or maids', several young men, 'preparing for up-country life', attended the evening sessions.
Elizabeth Gard'ner pioneered the teaching of home science in New Zealand and from 1897 was the first to train teachers in home science subjects. These early years were extremely hard. The school's financial position was always difficult and often precarious and the premises were rat infested. Although they moved to cleaner premises in Hobbs's Building, Cathedral Square, and then to a schoolroom in Manchester Street, conditions remained primitive and the hours were long. On 12 October 1898 Richard Gard'ner died.
As well as conducting large adult classes, Elizabeth Gard'ner introduced sessions for girls from Christchurch primary schools. Her reputation grew and she had stalwart friends in the managing committee and among inspectors and principals of schools. She was tall and stately with soft grey hair and a lovely complexion. Although she was gentle, no one took liberties with her.
Shortly after the Christchurch Technical College started its day school in July 1907, the School of Domestic Instruction combined with it. Elizabeth Gard'ner became head of the domestic science department and until 1911 continued to teach in the School of Domestic Instruction's newly leased premises at the corner of Worcester and Manchester streets.
After the merger, Gard'ner urged the establishment of a training hostel, where girls could live and receive instruction in all branches of homecraft. Ernest Shackleton was a supporter. He donated half of the proceeds from his 1909 Christchurch lecture as the nucleus for a building fund. John Studholme of Coldstream, who established a chair of home science at the University of Otago, was another generous benefactor. When the Girls' Training Hostel opened in Ensors Road in 1913, Elizabeth Gard'ner was the first principal.
Due to failing health, she resigned in 1916 and moved to her cottage at Clifton. However, she continued to serve the technical college as a member of the ladies' advisory committee and honorary examiner, and she also taught cooking to inmates at Addington Reformatory for Women. Together with Alice Harman, she compiled the popular New Zealand domestic cookery book, and she also wrote Recipes for use in school cookery classes.
Elizabeth Gard'ner died at Christchurch on 5 June 1926. After her death, subscriptions from friends and former pupils for a memorial fund were received by the ladies' advisory committee. The board of Christchurch Technical College and the minister of education, R. A. Wright, also made contributions. Two scholarships were established for technical college students who wished to train as home science teachers, and a memorial tablet to Elizabeth Gard'ner was placed in the hall of the Girls' Training Hostel.