Botanic Gardens are always interesting to visit, any time of year. Since there are 1,775 botanic gardens in 148 countries world-wide*, you may find one near you (you can search here).

The Cuningham House conservatory, which houses sub-tropical plants.
Winter roses (Hellebore sp.) – members of the buttercup family (Ranunculaceae).
Hyacinth flowering.
Ostrich ferns (Matteuccia struthiopteris).
Rosehips in The Heritage Rose Garden, near the Hospital.
Bark of Père David’s maple (Acer davidii).
Pine mound.
Nursery, near the Visitor Centre
Native plants, near the Visitor Centre.

There is a summary of the collections in the Christchurch Botanic Gardens here, more detail here, and a map here.