More than 150 guests are expected at the War Memorial in Napier on Friday to celebrate the opening of the Guthrie-Smith Tutira 20,000 tree Arboretum.
The special guests, including funders, supporters and sponsors, will also be invited to visit the arboretum, which borders Lake Tutira and Lake Orakai in northern Hawke's Bay, on Sunday.
It will then be open to the public every Sunday until the end of next May, and then reopen from October until May every year.
Associate Professor Alex Calder, head of English, drama and writing studies at the University of Auckland, will attend on Friday as the guest speaker.
He believed Herbert Guthrie-Smith, one of the area's leading settlers, was also "one of the first environmental historical writers and is a key person to turn to, to understand why rural New Zealand looks and is the way it is".