Moana House programme director Claire Aitken awaits the arrival of Christmas trees for the annual fundraiser.

Christmas is a time for second chances, even for the invasive weeds choking some of the country's natural landscapes.

Those weeds are wilding pines, which are planted and grown in West Otago's Blue Mountains, then cut and sold as Christmas trees by a group of ex-cons fundraising for Dunedin's Moana House.

Moana House has about 20 men on a year long rehabilitation programme, transitioning them from prison back to society.

"We deal with people who have complex problems, who need a lot of input and assistance to get back on track," programme director Claire Aitken said.

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Sales of the festive tree kicked off this week, continuing a 31-year tradition often marked by a Māori Santa waving at the dozens of buyers waiting each day.

The over-representation of Māori in prison meant the annual job of wearing the red suit and white beard resulted in their own unique annual tradition.

"Some of our Santas have had full facial moko, and no-one bats an eyelid", Aitken, in a nod to the furore over the recent Nelson Santa parade, said.

Each December cutting and selling Christmas trees has been the stalwart fundraiser for the residents – usually about 1000 are sold, starting at $10 a trunk.

Some give more for the sale, but those who can't afford one don't walk away empty handed.

"We want everybody to have a tree," Aitken said.

The Christmas tree gig requires a lot of preparation, participants are given first aid and chainsaw training.

This year's proceeds would help pay for repairs to the truck which hauls the trees around. But the main purpose was to connect Moana House residents and the community

The facility was groundbreaking when it opened in 1987, and "still is now", Aitken said.

The programme, which includes nine months residential care and three months after-care, has a waiting list of over 160 men from around New Zealand.

Aitken conceded the backlog would take years to clear, because this was a real chance to turn their lives around. For some it was as simple as learning to cook, speaking in a group, others recognised the impact their upbringing had on their life and their decision-making.

Many of the offenders were written off by society for crimes such as rape and murder, but the programme got tangible results because the 25-strong staff never gave up on them, Aitken said.

"We take a compassionate approach without being wishy-washy."

They knew despite years of criminality it was possible to turn around a person's life.

"You have to do in a very thoughtful way."