This paper assesses the contribution made by the cultivation of urban gardens to the food self-sufficiency of mountain municipalities at risk of food desertification during 2020 in South Tyrol (Italy). A food desert is a territory where people are food-insecure because of job/income loss or through the absence of food retail facilities. During lockdown, many non-essential firms were forced to close. This meant that many workers, especially those in more precarious positions, lost their jobs, while entrepreneurs had consistent financial shortcomings. Local population mobility was restricted to the municipality of residence, with reduced access to grocery stores outside that area. This insecurity left mountain municipalities increasingly vulnerable to desertification. To tackle this situation, several alternatives have been considered to increase food self-sufficiency, such as gardening. This paper contributes to the debate by presenting a Decision Support System (DSS) that calculates the land required for food self-sufficiency in South Tyrolean municipalities and the percentage covered by the production of local urban gardens.