920 native plants grown by Orewa College students as part of their Trees for Survival Trust programme have been stolen.
Community programme staff and students say they are disgusted by the theft.
The plants were to be planted by the students on Monday to help improve the stream water quality and stabilise land at a local farm.
The theft occurred at West Coast Road, Ahuroa where the plants were being kept in a paddock by the roadside until the planting day.
The plants were 40-50cm high and stored in milk crates.
Gael Ogilvie, manager of Auckland Council Environmental Services said it was a thoughtless act.
"It's the exact opposite of the kind of behaviour that the students showed by growing these plants for a good cause."
Trees for Survival is an environmental education programme supported by Auckland Council. It involves young people growing and planting native trees to help landowners revegetate erosion-prone land, improve stream flow and water quality, and increase biodiversity.
The programme also creates community partnerships by engaging schools, their community, local businesses and councils, working together to restore our natural heritage.
Currently there are over 5000 school students involved in the programme with more than 70,000 trees planted each year. In the past 20 years, the trust has planted more than a million trees
Anybody with any information about the theft of the plants should contact Helensville Police Station on 09 420 8967 or anonymously call Crimestoppers on 0800 555 111.