BNZ staff members were given two paid volunteer days a year, which were mainly used individually before Closed for Good began in 2010.
Groups and organisations were asked to submit projects for consideration two months ago, and BNZ tried to send staff to as many projects as possible.
Mr Luxton said applications for help were open to anyone, and resulted in a huge variety of project types. Last year he helped replant the front of Kowhai Park after the flood, and in the past has given online fraud protection advice to older people.
St Mary's School principal Jacqui Luxton said a group of senior students had spent part of the year planning the new garden space. She said it was fantastic BNZ got stuck in to help kick the works off.
She said the area would be a vastly improved student space, and would have grass, a tree, an aviary and a sacred space for pupils to spend quiet time in.
"For me it's about having friendly spaces where kids can hang out and relax," Mrs Luxton said.
She also said a vegetable garden at the back of the area would provide food for local families, which students would tend to.