Swathes of unused space in London, including flat roofs, are to be converted into vegetable gardens in an initiative that gives a new meaning to the slogan “Dig for Victory”.

Roof gardens, disused railway yards, housing estates and school gardens will be transformed in a push for sustainability by Boris Johnson, the Mayor of London.

The unused spaces are to be converted into rows of potatoes, tomatoes and brussels sprouts in a green drive with a lofty aim: to feed the 2012 Olympians with products grown in the capital.

The flat roofs in London offer an area roughly 24 times the size of Richmond Park, and Mr Johnson's aides have been trawling the city to find them. Owners will be offered incentives to convert their space into a fertile environment and be provided with necessities such as tools and compost.

The Times has learnt that the mayor intends to create 2,012 new growing spaces in time for the Olympics, in the hope that some of the food will be provided to athletes.

It will be a 21st-century twist on the Second World War slogan “Dig for Victory”, an exhortation to grow vegetables. In recent years, as environmental awareness has increased, growing vegetables on allotments has been more popular across the country. However, London produces little of its own food.

Rosie Boycott, the former newspaper editor and chair of London Food, which is funded by the London Development Agency, hopes that the conversion of flat roofs and other unused space will vastly increase the amount grown. She told The Times yesterday that she would like to achieve a “sea of green in the air”, as roof gardens were ideal for vegetables. “They also help reduce flooding, improve insulation and take carbon dioxide out of the atmosphere,” she said. The programme would encourage community consumption of food, as supplies would be sold at markets.

Hospitals could grow food for their canteens, while vegetables from communal gardens could be distributed among the owners.

“This accommodates anything, from roof gardens to gardens in youth offender institutions, to canal banks and banks of reservoirs - the lost pieces of land that are just gathering dust,” she said.

Hotels, businesses and residential complexes with communal roof gardens will all be approached when the initiative, inspired by American cities, is launched tomorrow.

In Chicago the authorities have encouraged widespread cultivation of roof gardens and numerous markets are sustained by household produce. Food is grown in ornamental gardens in its central park.

Sustain, a food and farming alliance, is co-ordinating the programme for Mr Johnson. A website will be set up to put growers and landowners into contact. Ben Reynolds, Sustain's network director, said: “During the Olympics we want to be providing an image of a sustainable city that we can be proud of. Roof gardens are a way of reducing pollution and improving air quality, as well as producing food.”

Ms Boycott has discussed providing vegetables for athletes with the Olympic Delivery Authority. “The eyes of the world will be on London and it is very important that it is as sustainable as it can be,” she said.

Mr Johnson has extolled the benefits of rooftop gardens, pointing out that they utilise rainwater.

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