Metiria Turei says National, not the Greens, is the radical party in New Zealand because of policies which have damaged families and the environment.

In her State of the Nation speech this afternoon in Wellington, the Green Party co-leader reached out to voters who had reservations about her party and believed it was too "outlandish" and "audacious" to run the country.

"I want to talk about these reservations ... and tell you why you can trust us with your vote and with the responsibility of running the country," she told an audience at the National Library.

"And I hope to convince you that you should do this now. Because it's a lot easier to not make a mess in the first place than it is to clean one up."


She said the Green Party was often dismissed as radical, but when its policies were adopted by the National-led Government they were described as conventional.

Its ideas on housing insulation, rail electrification, a capital gains tax, and public transport had been adopted by the Government.

The Greens were the first party to talk about climate change, and this issue was recognised by the Government at the landmark Paris accord in December.

"There are two lessons here," Mrs Turei said. "The first is that ideas that are attacked as radical when the Greens propose them become conventional, sensible solutions very quickly when other parties adopt them.

"That tells us something about the gap between perception and reality when it comes to the Green Party.

"The second is that if you still think Green ideas are too radical for government then you have a problem.

"Because no matter which party you vote for, a lot of the new ideas and new solutions still come from us."

She suggested that the Greens were "a fairly conservative party" on social, environmental and economic issues.


Doubling the dairy herd, increasing pollution, and proposing to mine national parks, on the other hand, was radical policy, she said.

"We think the economic experiment imposed on our country over the last thirty years is radical ... We think the steep rise in child poverty and poverty-related child death is radically irresponsible.

"It's not radical to stand against the disintegration of our environment and our society. It would be radical not to do so."

Mrs Turei said the Greens wanted more longer-term thinking in New Zealand's law-making, and cited former Labour Prime Minister Michael Joseph Savage's state housing and free healthcare reforms.

The Government, she said, was taking the easy route and making minimal changes.

The Green Party co-leader also announced a new policy to create an independent unit within the Treasury which would calculate the cost of each party's policies ahead of an election.

Mrs Turei said the National Party got away with not costing its policies because there was a perception that it was trustworthy and sensible on economic issues.

"The asset sales are a good example. John Key pitched it as freeing up $7 to $10 billion dollars. They got $4.7 billion dollars ... We got scammed. And no one even blinked."

She said the proposed Treasury unit would make elections more about ideas and less about spin, and give New Zealanders unbiased information during an election period.

The party has written to all party leaders to seek their support for the policy.