Participants collected food purchase receipts for their household over a one-month period which constituted a detailed record of the quantities of food entering their household. They were asked to save all till receipts for foods consumed at home. To facilitate data collection, participants were given a notebook of food purchases in which they could find step-by-step instructions, example receipts, and, on the last page, an envelope in which to collect the receipts. In case of incomplete or ambiguous printed information regarding the name of the shop, the name of a food, the quantities purchased or the price paid for a food, participants were instructed to write it on the receipt. Expenditure without receipts and food items coming from the garden, or from gifts or social aid services were to be recorded in the notebook. The participants were also requested to ask other household members to keep their till receipts.

An informative questionnaire enabled the characterization of the 21 participants by gender, age, country of birth, number of household members, occupational status of the gardener and household members, and the gardeners' perception of their financial situation. The agronomic part of the questionnaire provided information on garden use (past gardening experience, length of time in the current plot, time working in the garden), production management (choice of crops and cultivation practices, soil knowledge and preparation, seed and plant origins, methods of crop protection, training and learning methods,exchanges with other gardeners), and garden functions as perceived by the gardeners, together with their motivations for gardening.