The Ōtari-Wilton's Bush plant collections contain about 1,200 species, hybrids and cultivars. The collections include plants from New Zealand's mainland and off-shore islands.   

Almost all the plants have been grown from cuttings or seeds collected from their original habitats. The collection has the following roles:

• Conservation: Seedlings of threatened species are raised and either kept in the gardens as a conservation measure or returned to the wild in plant conservation recovery programmes. 

• Research: Scientists use the plant collections for studying plant ecology, economic potential, and classification. 

• Education: Plants are labelled to help visitors learn about their names and characteristics. 

• Recreation: Ōtari-Wilton's Bush is a great place for locals and tourists to escape urban life and appreciate New Zealand's unique flora. 

The plant collections were started in 1926 by eminent New Zealand botanist Dr Leonard Cockayne. He aimed to set up a collection of solely New Zealand native plants, displayed in family groups or as re-created ecosystems representing different areas of New Zealand.