Award-winning botanist and author Philip Simpson gave a public presentation in the centre and led a tour focused on trees at O'Connor's Bush and the Greytown park camping ground.
Mr Simpson was a founding trustee of Project Crimson, which aims to protect pohutukawa and rata, and in 1999 was appointed as South Island advisor for the project after 20 years with the Department of Conservation.
He wrote Pohutukawa and Rata: New Zealand's Iron Hearted Trees and Dancing Leaves: the story of New Zealand's Cabbage Tree, Ti Kouka.
Mrs Gray said weather had forced the postponement of a Matariki planting on June 29 although the next day there had been an Arbor Day planting of apple trees in Stella Bull Park in the town.
Kuranui College pupils had dug holes at O'Connor's Bush before the holiday break and had eased the lot for workers, she said, who completed the planting in about an hour on Saturday.