If there aren't such cultures grown, this may be considered as a place for leisure(something as an outdoor_seating).  In Bulgaria there are many such spaces around the apartment blocks for example. They may be tagged as parks, leisure=outdoor_seating etc. In Bulgarian such a place might be often mentioned as "градинка", which does not absolutely mean that this place is made for plant growing. (https://wiki.openstreetmap.org/wiki/Key:garden:type) From the wiki:
Located in parks or other public spaces, community gardens are operated by an informal group of local residents. To some, community gardening is a leisurely social activity. To others, it is a response to concerns about food security. See Community gardening. (Compare landuse=allotments, individually tended plots.)