In 1972, alarmed over the increasing political violence in Northern Ireland, McGredy and his family moved to Auckland, New Zealand. He transplanted his nursery stock and renamed the company, "McGredy Roses International". New Zealand's climate, ideal for plant cultivation, allowed McGredy to breed roses outdoors without greenhouses. He soon introduced a new series of what he called 'hand painted' roses, brightly coloured striped roses and roses splashed with two or more colours. Some of his most popular rose cultivars include "Rosa" 'Dublin Bay, "Rosa" 'Sexy Rexy', and "Rosa" 'Handel'. When McGredy retired in 2007, he closed the nursery. He died in 2019.