Fresh vegetables can be expensive at Christmas time, but needy Auckland families will be able to get some for free this year courtesy of New Zealand's toughest prison.

Boxes filled with fresh prison-grown veggies have been donated to the Salvation Army to distribute among families and individuals.

The produce is all harvested under the watchful eye of Corrections Horticulture Instructor Don Gillanders.

"Most of it goes to the Salvation Army and we're hoping to go to the Auckland City Mission in the near future," he said.

Gillanders said working in the prison's gardens had a real and positive impact on the men inside and as an added bonus they got qualifications for it all.

In the last calendar year, he said the men had spent about 10,000 hours working towards primary industry certificates that would help towards outside employment.

This season more than five tonnes of vegetables had been donated by the prison, but next season the men hope to far surpass that and provide seven.

One inmate, who for privacy reasons Radio New Zealand is calling Max, said he was grateful for the opportunity to help others.

"In most of the other units I've ever been in we don't get a chance to start giving back, or to try and do something good," he said.

"So this has been a really big thing for the men."

He said the garden was also a good place for the men to sit and reflect after sessions with their psychologist, where their offending was addressed.

Once harvested, the veggies were picked up by Judith Newton from the Salvation Army and taken to be distributed to families and people in need.

"We have a lot to do with the homeless, people who haven't got much money and are quite poor," she said.

"To have these wonderful vegetables is a huge boost to us being able to give people this wonderful food."

Newton said some of the recipients were so enthused by the vegetables they had even started their own veggie gardens.

And when new people came for food, they were overwhelmed to hear it came from the prison.

"They're just absolutely overwrought by the whole thing that the prison can help them and help us so it's a good vibe, a very good vibe."

