Hackfalls Arboretum, Tree reserve in Tiniroto, New Zealand.

Hackfalls Arboretum covers 0.56 km² of Hackfalls Station, a sheep and cattle farm near Tiniroto. Its roughly 3,500 trees and shrubs stand in rolling pasture, each oak limbed up so grass grows underneath. The collection includes about 450 oaks, among them some 50 taxa of Mexican oaks, plus around 400 rhododendrons and 220 poplars.

The Whyte family from Scotland first settled the land as 'Abbotsford'. The Berry family, originally from Knaresborough in Yorkshire, bought it in 1916. From 1954 Bob Berry planted willows and poplars, then oaks, collecting acorns from commercial suppliers in 1961 and 1962 and from the Melbourne Botanic Gardens in 1966. The name Hackfalls was adopted in 1984.

The International Dendrology Society recognized Hackfalls Arboretum in 2002 as a collection of outstanding merit through a bronze plaque installation.

Access is via Berry Road, a side road off the gravel Ruakaka Road about 1 km from Tiniroto; the homestead is 3 km further, past Lake Kaikiore. The station spans 120–388 m in altitude and receives about 1,650 mm of rain a year, with light snowfalls possible in winter. Most of the arboretum is grazed by sheep, so expect livestock and wet ground underfoot.

Bob Berry joined an International Dendrology Society tour of Mexico in 1982 and sowed the seed he brought home; return trips followed. The Mexican oaks are considered the most extensive collection of their kind outside Mexico. Other New Zealand firsts credited to his Mexican wild collections include the tree dahlia Dahlia tenuicaulis and Clethra mexicana.