Undeveloped natural forest, bushland and mangroves cover about half of the Garden. This largely represents the original vegetation of the area; however protection from fire over a long period of time gradually changes the nature of the bush as fire-sensitive plants, such as gristle ferns and screw ferns, increase in the understorey changing the normal mix of groundcover plants.
The vegetation is not uniform throughout and various types may be seen. Drier Eucalyptus species grow on the higher slopes on the western side of the main track. These are gradually replaced down slope with swamp species and eventually mangroves along Coffs Creek. The main path is the dividing line between the dry and wetter habitats where ferns and palms are the predominant species.
Upslope to the west of the main path is dry sclerophyll forest. Typical species to be found here are Blackbutt (Eucalyptus pilularis), scribbly gum (Eucalyptus signata), pink bloodwood (Corymbia intermedia), red mahogany (Eucalyptus resinifera), turpentine (Syncarpia glomerulifera) and black she-oak (Allocasuarina littoralis). The understorey contains many species of wattles, banksias, bush peas, ferns and wild parsley. Several ground orchids may be found in the area – the winter blooming pixie cap and helmet orchids, and the swamp orchid (Phaius australis) that is recognised as one of the most threatened plant species in NSW.
On the Coffs Creek side of the main path where drainage is poor, the forest species vary according to the duration of waterlogging and the degree of salinity. Swamp mahogany (Eucalyptus robusta) up to 25 m tall grows at the base of the hill, whereas the broad-leaved paperbark (Melaleuca quinquenervia) forms a forest up to 10 m tall in areas of prolonged inundation. Swamp she-oak (Casuarina glauca) occupies a narrow band closer to the creek where there is some salt influence.
In the tidal zone there is a dense forest of grey mangrove (Avicennia marina var australasicum). However wherever the salinity is reduced by proximity to stormwater channels, or when proceeding further upstream, the shrubby river mangrove (Aegiceras corniculatum) tends to predominate.