
Assistant prison director Gill Brown said the prison started a large recycling project that takes milk cartons used by the facility and recycles them for horticultural projects.
The cartons are cleaned by prisoners and have holes stamped in them.
The stamping press for the cartons was designed and built by one of the prisoners studying and learning in the prison's carpentry workshop.
They were given a brief to produce a tool that could punch holes in the bottom of the milk cartons to allow for the free flow of water and root growth.
It was made with no moving parts or blades, making it safe to use as well as being simple and effective.
Ms Brown said it provided an excellent opportunity for the prisoner to take on the brief, speak to the customer about the problem and design a solution to take it through to a product.
``There's some real pride in that.''
It was important for people in prison to be busy doing meaningful things as it helped pass the time and provided some structure in their day.
``These prisoners can get involved in ongoing work which has purpose and provides them with a sense of achievement.''
Ms Brown said the recycling project was great for engaging prisoners who were unable to do more physical work.
The correctional facility was always looking for ways to be more environmentally friendly, she said.
Acting prison director Lyndal Miles said each prisoner received two cartons of milk per day as part of the prison menu.
``This adds up to 4800 milk cartons a week that could otherwise be going to waste.''
The recycling project was the first phase of a development in an environmental collaboration between the prison's carpentry workshop and the horticulture team.
The cartons are filled with suitable soil for seeds and seedlings and then placed on a heated propagating table to stabilise the soil temperature.
Wild-sourced seed for the Hokonui wetlands horticulture project is cultivated for the prison's horticultural growing programme
Many of the seeds sourced for the wetlands project are being replanted in the cartons.
In the first three months more than 500 cartons reused, Ms Brown said.