Claire Trevett: Still Green inside the packaging

One of the important things about Green Party conferences is that they serve to remind the public and MPs that despite all that new professionalism and slick marketing, there remains a healthy dollop of what the Greens are known and loved for.

This year, a new group - the Spirit Greens - has been set up and at the conference has been beckoning "those of any faith, on a spiritual journey or who want to be on one". Stickers with "humans" written on them have been put over the "men" and "women" on the toilet doors.

Metiria Turei may well represent, as she says, "the changing face of Aotearoa New Zealand" and the party may well be, as outgoing co-leader Jeanette Fitzsimons says, more professional than the party of yore.

Yet when she was elected the new co-leader, Ms Turei promised she would bring no radical change. Instead, the catchphrase - used by both Ms Fitzsimons and Ms Turei - was of "fresh energy, fresh face, but the same cause".

Ms Fitzsimons also pushed the message that the party was stronger than any one person, driven not by the personality of its leaders, but by the efforts of its grass roots.

Although there was broad support for Ms Turei, change can be de-stabilising and party members - at least in the short term - are less likely to let the parliamentary wing's actions go unchallenged than they had been during Ms Fitzsimons' reign. The Greens are very fond of their consensus-style decision making, yet the deal with the National Party was done before the members were fully consulted. Despite this, at the conference there was precious little disgruntlement about it. The reason for that is largely because the trusted hand of Ms Fitzsimons backed it.

Ms Fitzsimons was from the rural, environmental side. Ms Turei and the other co-leader, Russel Norman, are city-dwellers, academic, and more strongly associated with the social justice wing. There will be those wary that this could dilute the focus on core environmental issues. Over the weekend, Dr Norman and Ms Turei were careful to push the work they were doing on clean waterways and Resource Management Act reform to build their environmental credentials.

This conference was more critical than others. The Greens are, in many ways, at a crossroads they have not seen since entering Parliament in 1996.

Both the founding leaders are gone. After nine years, their more natural ally Labour is no longer in government and the time is ripe for the party to assess where it is. Despite the claims no radical change is under way, it is changing. One of Sue Bradford's concerns when campaigning for the co-leadership was that the party was becoming over intellectualised.

The party's "Green New Deal" is a case in point. The deal is actually old Green beliefs wrapped up with snazzy modern marketing. Take away that marketing, and it is a good marriage of the social justice and environmental beats, a comprehensive list of infrastructure and research and development spending on "green" projects aimed at creating jobs while simultaneously helping the environment.

It is thorough and targeted at two modern problems, but the response has hardly been overwhelming so far. It will be the job of Ms Turei and Dr Norman to change that.

A significant portion of the Green vote base is young. But its core membership are older, the activists from the 1960s and 1970s, the rural farmers. Ms Turei and Dr Norman are the two youngest members of the caucus.

The challenge for them will be to find a balance between attracting that new support base without alienating the old. For woe betide any leader who ignores those grass roots.