Since 1997 it has had waahi tapu status (sacred) under the Historic Places Act.
Under an agreement between the council and Forest & Bird, the organisation will visit the site regularly to carry out weeding and to water the plants.
It also plans to be involved in further plantings in the years ahead.
Forest & Bird project co-ordinator Linda Johnson said she was pleased with the number of volunteers who turned up on what was a cool, foggy morning yesterday.
"Everybody chipped in and did really well. We were most impressed," she said.
"Next year the kids can go back and see how tall the plants have got."
Mr Cave said the project was "a great mechanism to engage with the community and to realise the restoration and enhancement objectives of HBRC's regional parks".
Forest & Bird contributed about 100 of the native plants to the project.
Honda New Zealand's TreeFund, an initiative under which the car company supplies a number of trees for each vehicle it sells, supplied the rest of the plants.