Only 6% of vegetables served in Welsh schools are grown in Wales - with the rest imported.
Charity Food Sense Wales is trying to increase that figure to 10% sourced locally and organically by 2028, warning far more growers need to be found.
It said issues such as climate change and global instability are pushing up prices of food from abroad, meaning action is needed now for the benefit of future generations.
The Welsh Veg in Schools project, co-ordinated by Food Sense Wales, has Welsh government funding until March 2025, with a spokesman saying it will also be considered for support during the 2025-26 financial year.
Emma Evans and her husband Geraint have run a fruit and vegetable growing business on a nine acre plot in the Vale of Glamorgan for three years.
They described the project as a lifeline, with Emma adding: "We thought we'd grow veg and people would just buy it, but it's not that easy.
"You need to build a reputation.
"We only want to sell what we grow."
Food Sense Wales founder Katie Palmer said Welsh businesses are currently only growing enough vegetables to provide every person in Wales with a quarter of a portion.
"More growers like these are needed," she said.
“Building our own supply base is vital.
"This would reduce our reliance on imports through connecting local growers with local wholesalers."
She added: "It's not an easy task and we have got a big ambition to get 10% of the veg that's going into schools grown organically in Wales.
"Before this project that was practically zero."
It now wants to bridge the gap between how much the product is sold for and how much it costs to produce sustainably in Wales.
The charity wants to extend this across the public sector in Wales, getting all organisations using Welsh produce.
Ysgol St Baruc in Barry, Vale of Glamorgan, is part of the project and kitchen manager Georgina Thomas has been using locally-sourced vegetables.
"I've made a pasta bake for the kids," she said.
"We've hidden in there courgettes, butternut squash, onions and we've roasted it as well so they can have some on the side as well."
Blossom calls herself "a bit of a fussy eater" but is enjoying the vegetables, while Mollie said: "I honestly feel lucky because not many people can grow their own vegetables locally.
"They have to buy it at the supermarket."
Food wholesaler Castell Howell, based in Cross Hands, Carmarthenshire, is playing a big role.
It currently supplies ingredients for 700,000 school meals a week at 1,000 Welsh schools.
Talking about what they do, group manager Edward Morgan said: "The sooner the veg gets harvested, the quicker we can get them to the depot, and the quicker we get them in to the schools, and we lose less nutritional value."
The plan in the future is for companies such as Castell Howell to get as much locally-produced vegetables to children as possible.
A Welsh government spokesperson said: "The project has already helped to develop capability and capacity amongst local growers to supply the public sector."