The trees are only known to grow naturally in a single creek catchment in warm temperate rainforest in the Nightcap Range, northern New South Wales, Australia, referred to in the original description paper as "in Nightcap National Park and in the adjacent Whian Whian State Forest", more specifics of the recent (2000s) Nightcap NP collecting locality being undisclosed; a previous specimen was collected earlier, by L.J.

The trees grow naturally in relatively poor, acidic volcanic soils, in an area of a high rainfall.

[7] However, the plant has the ability to survive fires by coppicing itself as well as reproducing with its large seeds, and less than a fifth are thought to have died.

[8] Eidothea hardeniana trees have pale lichen covered bark typical of many species in the Warm Temperate Rainforests.

[citation needed] These toxins do not deter rodents from eating through the hard nut and devouring the seeds, limiting the regeneration of this plant.