The Ohinetahi property lies in a protected valley in Governors Bay just 20 minutes over the Port Hills from Christchurch. It is surrounded on three sides by a steep volcanic crater rim while the view to the north-east sweeps straight out across Lyttelton Harbour and Banks Peninsula.
A garden was first made on this site in 1865 by T H Potts one of New Zealand’s first botanists. He planted a great variety of exotic trees and shrubs, many of which stand on the perimeter of the garden. He died in 1888 and thereafter the garden fell into disrepair until it consisted of little more than a lawn around the house.
Sir Miles Warren and Pauline and John Trengrove restored the house and began the present garden in 1977. Designed by two architects and an artist, the garden inevitably has a strong architectural frame. The formal garden consists of a number of separate garden rooms of differing style and character arranged about two axes running east west and north south.
On the side of the house there is a formal lawn curved macrocarpa hedges at one end balanced by a pool and poolhouse at the opposite end. There is a rose garden enclosed in box hedges, traditional double herbaceous borders leading to a gazebo, a square walled garden planted in colours of red and green, and a walk of pleached hornbeams on stilts leading up to an oval lawn,
Beyond the poolhouse there is vegetable garden and glass house. From the oval and the gazebo, steps lead down to a woodland garden shaded by Potts original great trees with a stream flowing down to the harbour. It is densely planted with rhododendrons, camellias and a good variety of New Zealand ferns and native plants. A swing bridge extends the cross axis to the bush walk.
In 2008 the garden was enlarged by the purchase of 0.75 hectares of land with splendid views overlooking the harbour. Stone edged paths now lead to an amphitheatre and the steeper slopes have been planted. In recent times a number of large modern sculptures by renowned New Zealand artists have been installed in both the park and garden.
In 2010 the house was severely damaged by the earthquakes. The stone walls of the three storey block were badly cracked and the four gables fell. The house has been rebuilt and earthquake strengthened but now the central block is two storied not three with a strengthened masonry ground floor and a new timber framed first floor. The loss of the stone façade rising high above the lower roofs commanding the garden is regrettable but the new hipped roof at the same pitch as the single storey blocks pulls the three blocks together. All the stone constructions in the garden, walls, towers and follies have been restored.
In the grounds there are two galleries displaying a collection of New Zealand artwork and an exhibition of Warren and Mahony architecture.