Among the various forms of urban agriculture that have emerged and been developed over the past 15 years in countries of the global North, collective gardens (CGs) are one of the most significant. In Montreal and Paris, their numbers have increased rapidly in the past 20 years. Previous research has shown that food production is an important motivation for urban dwellers to engage in gardening activities, but the food function of CGs, that we define as the quantitative and qualitative food supply they are likely to provide to gardeners, is poorly known. This paper investigates this food function in Paris and Montreal. We carried out comprehensive interviews with gardeners, quantified production, and did plot monitoring to provide insights on the quantities of fruits and vegetables produced in CGs, the destination of garden produce, the use of space in plots, and the types of crops grown in CGs and their yields. The results show a wide diversity of practices regarding CGs' food function that has to be considered in relation to the multifunctionality of these gardens. The paper concludes with a discussion on the results and the implications of this research for garden planning and management.