Born in 1865 in Clunes, Cronin began working as a miner in the area, before relocating to Melbourne in 1886 where he found a job at the Royal Botanic Gardens.
After ten years with Guilfoyle, Cronin was hired by the Department of Agriculture as an orchid inspector.
Unlike his predecessor, Cronin was strictly a horticulturist and did not concerned himself with other matters like landscape design.
[4] During this period he built strong links with the gardening public, and carried out experimental breeding of ornamental flowers including tree dahlias and Watsonia plants.
Many of the flowers that Cronin bred, which bloomed in spring and were named after places in Australia, were released in the 1920s, most of which remain extant, albeit nameless.