The Trust was proceeded by The Friends of Bason Reserve, which was formed on 16 August 1982, five months after the gardens were officially opened. The purpose of the Friends was to support the then Wanganui City Council in the development of the gardens as an amenity for visitors to Whanganui and elsewhere, and for botanical and conservation purposes.

The role came to include the protection of bequests, ensuring that they were used for both the benefit of the gardens and to protect the wishes of the donors. The main chairmen during the developmental stages were Keith Burtt and Ross Macdonald.

On 14 April 1998, Bason Botanic Gardens Trust was incorporated as a Charitable Trust, with Ross Macdonald as founding chairman. The purpose of the Trust was to support development, to promote botany and conservation, to encourage public access, and to raise and manage funds.

As the gardens have matured, so too has the role of the Trust. Today, the emphasis is shifting from capital development to education and engagement of the public at large in things botanical and environmental, cultivating the relationship that has long existed between people and plants.