William Ferguson migrated to Victoria circa 1856, and was appointed to the public service as inspector of state forests on 1 September 1869. It is possible that he first worked on the private estate of Mr Hugh Glass at Flemington in the late 1850s-1860s, helping to establish a large plantation of exotic trees (see Third Annual Agricultural report of 1875).

On 16 December 1869, Ferguson commenced duties in the Royal Botanic Gardens Melbourne, where he was also placed in charge of landscaping and practical work. This latter appointment was a constant cause of friction and irritation to the Director (Ferdinand von Mueller) who felt humiliated and bereft of proper authority. Ferguson's interference with the running of the Botanic Gardens lasted at least until 1872 ( Margaret Willis By Their Fruits (1949), pp 92-97, 109, 126). By 1874 he was stationed at Macedon, presumably in charge of the young State Nursery there, and he supplied the new Director of the Botanic Gardens (William Guilfoyle) with local ferns and other plants.

On 6 October 1886 Ferguson was interogated by the Royal Commission on Vegetable Products [Third Progress Report' of The Commission, 1886, pp 137-160], and in December 1889 James Blackburne was appointed inspector of forests, presumably upon the retirement/resignation of Ferguson [Report ofthe Conservator of Forests, June 1890], where Mr Firth is cited as the current superintendent at Macedon State Nursery.