The flourishing trend of children planting and tending vegetable gardens at school is under threat from cuts to a state-funded nutrition scheme, the Public Health Association conference was told.

More than half of schools have "edible gardens", research presented to the conference indicates.

Otago University postgraduate student Carly Shaw - who surveyed 1146 schools - said funding concerns and vandalism were big barriers to schools starting a gardening project, and there was anxiety about their future.

Many relied on funding from the Government's Healthy Action/Healthy Eating (HEHA) programme, distributed through the local district health boards, and on non-financial support from its Enviro-schools scheme, Ms Shaw said.

But the Government's cutbacks are reducing HEHA spending by DHBs and the Health Ministry and ending, from next December, state spending on Enviro-schools, although at least one city council has stated it will increase its commitment to Enviro-schools.

Ms Shaw said starting a new garden would be much more difficult without the funding.

Keeping an existing one going was not so reliant on this because it produced seeds for the next season and parents became involved.

"You will see schools that have set up links to their community will be okay because local businesses will get involved. For those without that, I'm not sure."

Ms Shaw said responses from the two-thirds of schools approached which replied to the survey gave insights into how varied schools' edible gardens were and showed how beneficial they were for children.

Some schools had planted traditional vegetables such as lettuces and carrots, but one told the researchers it had planted lavender to use in icecream with honey, while another was growing grapes.

"One school sent pictures of a kayak; they had a garden in a kayak."

Ms Shaw cited US research linking nutrition education based around gardening with improvements in the preferences and consumption of fruits and vegetables.

"This improvement has been more successful at influencing health behaviours than other school-based initiatives."