The flowering plants at Tireragan include a wide range of species from orchids to heather to trees and water plants such as bogbean and water lily.
In the woodlands, the under story contains a rich array of herbaceous flowers and grasses. Native tree species in found in Tireragan include the sessile oak, hazel, rowan, aspen, alder, eared willow and downy birch.
On the heath and moorland, small shrubs such as bell heather, ling, bog myrtle and creeping willow predominate while the bogs contain grasses such a cottongrass and insectivorous plants such as sundew and butterwort.
In the pools and lochens bogbean and water lily are common, while the dry sandy areas behind the beaches are home to flag iris, biting stonecrop and mayflower.
On the exposed rocky slopes above the sea juniper is common while closer to the water thrift and sea campion thrive in betwen the rock.