Frederick William Hilgendorf was born at Waihola, Otago, New Zealand, on 23 January 1874, the youngest of four children of Elizabeth Benstead and her husband, Charles Augustus Gustavas Hilgendorf. His father was a German-born public works and mining contractor, also listed as a storekeeper; his mother was a governess. Frederick attended primary school at Waihola and Dunedin, and later attended Otago Boys' High School; he described himself as an indifferent pupil. He spent most of his leisure time out of doors, swimming, boating and tramping, and collected a notable set of birds' eggs. In 1893, in his second year at Dunedin Training College, he enrolled for his BA, but failed terms in two of three subjects. Then he settled down to his first hard study, winning the Senior Scholarship in zoology and graduating MA with first-class honours in 1896.
Working in his vacations on a goldmine at Waipori with his father, Frederick Hilgendorf learned practical geology and surveying, and how to get on with independently minded men. Charles Darwin's On the origin of species was his reading in the wilderness. On a tramp from Taieri Beach to Waipori he and his medical student friend, Charlie North, practised comparative osteology on skeletons of sheep and rabbits. He considered that this journey determined his career as a biologist.
Hilgendorf taught school briefly at Taieri Beach and at Prince Albert College, Auckland. While there he completed his BSc degree, was president of the students' association and the debating club, and started the Auckland University College Football Club. In 1899 he was appointed lecturer in natural science at Canterbury Agricultural College (later Lincoln College). He later confessed that 'When I started I didn't know a single grass or weed, although I could distinguish wheat from oats'. With the guidance of William Lowrie, a new and inspiring director, Hilgendorf and his students began to teach themselves, working on the college farm and ranging over the plains and beyond the mountains by bicycle. The spirit of free but disciplined enquiry which Hilgendorf introduced to a training course for aspiring farmers led naturally to research, and later to handbooks that students still use.
From 1902 to 1903 Hilgendorf taught science and mathematics at Southland Boys' High School, augmenting his income by giving extramural lectures on agricultural chemistry, and by providing a weather report for a local paper. He married Frances Elizabeth Murray at Lincoln village on 26 August 1903; they were to have two sons. Hilgendorf returned to the agricultural college in 1904 with a traction-engine driver's ticket, earned by stoking a reluctant boiler with 'wet sawdust and lignite' on a night-shift.
The University of New Zealand awarded Hilgendorf's DSc degree in 1905 for his (unpublished) work on rotifers. He soon stamped his mark on Canterbury science, giving papers on several aspects of biology and geology to the Philosophical Institute of Canterbury. He was an energetic presence on the institute's committee, biking in regularly from Lincoln, and served as president in 1907. By that date he was explaining the recently rediscovered laws of Gregor Mendel, the founder of modern genetics, to students, farmers and university professors. In 1908–9 he was interim director at Canterbury Agricultural College.
In 1909 Hilgendorf began selecting uniform lines of wheat from the very mixed cultivars being grown. His early success with college hunters established his reputation among farmers. He was a cunning experimenter, rigorous in the interpretation of his results. From about 1912 he began to design experiments which enabled reliable generalisations to be drawn. His insistence on a rigorous methodology which would result in valid conclusions set him apart from his contemporaries in New Zealand. In 1923 he and J. W. Calder published a paper in the New Zealand Journal of Agriculture which set the standard for future field trials in New Zealand.
In 1921 Hilgendorf was elected a fellow of the New Zealand Institute. He spent a short sabbatical at the University of Cambridge in 1922, during which he learned about new techniques for breeding wheat. After his return his experiments outgrew the college's facilities. He induced flourmillers, bakers and farmers to co-operate with the Department of Scientific and Industrial Research to finance, establish and manage the Wheat Research Institute, set up in 1928; he became its first director. The institute included facilities for baking and milling in order to test both the quality and yield of new wheat strains, and engaged in activities ranging from courses for bakers' apprentices to studies on the theoretical basis of wheat-breeding. Its early major success with the new wheat Cross 7 served for many years to justify industry and government investment in science. Hilgendorf modestly attributed the institute's success to the lucky choice of Otto Frankel as its plant breeder, and H. E. West and E. W. Hullett as its chemists.
Hilgendorf published several books and pamphlets on agriculture. His 1935 DSIR bulletin, Grasslands of the South Island of New Zealand, encompassed much more than its title suggests, and as the first example of land capability maps was the last of his innovations in New Zealand science.
Always a lover of sport and the outdoors, Hilgendorf was a prime mover in the formation of the Ellesmere Rugby Sub-Union in 1906. In the 1920s and early 1930s he, his sons and various friends arduously climbed and mapped in the Waimakariri headwaters, or foolhardily shot its gorge on a petrol-tin raft.
After another spell as interim director of Canterbury Agricultural College in 1935–36, Hilgendorf retired from the staff in 1936. He joined its board in 1937, and continued as director of the Wheat Research Institute until his death at Wellington on 24 September 1942. He was buried in the Springston cemetery beside his wife, who died in 1930.
Frederick Hilgendorf was short and stocky – in his later years rotund; robust and adventurous in mind and body; wise in his conduct of professional and business affairs; and respected and greatly loved by his large circle of colleagues and friends. He had been New Zealand's outstanding teacher of agricultural biology and had made a major contribution to the development of the wheat industry.