Children from 12 Southwark schools spent the day at Borough Market on Thursday as they prepare to grow produce to sell to the public in the autumn.
Around 60 children took part in two sessions, the first led by Blue Peter gardener Chris Collins who talked to the young gardeners about planting seeds and caring for them over the summer.
The children then went off into the market to learn the ins and outs of what it takes to be a market trader, including the importance of presenting their stalls and basic customer services skills.
"Borough Market is a place where people come to learn about good food and why good food matters," said Keith Davis, managing director.
"The Harvest Sale programme is the perfect way to help educate the next generation on the importance of where their food comes from and teach them basic skills of nurturing seeds, seeing them grow into vegetables and experiencing first hand selling those vegetables at market."
Following the launch, pupils will return to their schools with the aim of growing the biggest and best vegetables to bring back to the market for the Harvest Sale on Thursday 10 October.
With pupils turned traders for the day proceeds from their vegetable sales will be donated to Walworth Garden Farm which provides environmental education and training in horticulture.
Stephanie Wood, director of School Food Matters, said: "Our pilot Harvest Sale last year proved to be such a hit with children and market customers that this year, with the support of the United St Saviour's Charity, we're back with a bigger and better programme.
"Our special thanks goes to the good folk at Borough Market who realise that the very best way to teach children about food is to get them growing it for themselves."
Chris Collins said: "It is always the most engaging experience working with children on such projects as the Borough Market harvest sale.
"Our natural affinity towards gardening really shines through in our younger friends and the importance of fresh produce and healthy eating becomes a simple message when they get their hands in the soil and grow food themselves.
"It is projects such as this and organisations such as Borough market and School Food Matters that are trail blazing this important work and it will be hailed as visionary in the future. It is also – and maybe just as importantly – really great fun."