A million extra trees and shrubs, mostly native, will be planted in Auckland over the next three years if Phil Goff is elected the city's new mayor in October.
The promise is included in the first part of Goff's environmental policy and is aimed at addressing environmental concerns and increasing green cover.
Goff called the policy the Million Trees Programme and said it would cost $1 million a year.
That would allow the council to provide practical support so the current planning programme could be expanded, with costs offset by partnering with businesses and iwi, he said.
"Many organisations like schools, the Department of Conversation, private entities and NGOs (non-governmental organisations), local boards and social groups, to name a few, already do great work in this space but there is a role for council to be involved as well.
"[The] council will work with local boards and encourage them to lead tree planting projects in their communities. I want this to be a community-led programme because our local communities know best what the needs are in their areas.
"Planting more trees, especially riparian planting, will improve the health of our harbours and rivers by preventing erosion and reducing salutation in the Hauraki Gulf, the Kaipara and Manukau Harbours, and our rivers and streams."
The plan would also help combat climate change and help New Zealand meet its Paris Conference on Climate Change obligations.
"Planting more trees will help beautify and purify our city. It is a win-win for everyone."