Intensive farming systems have led to reduced food availability for honey bees which could be related to their current decline. A global tool is needed in order to assess the melliferous potential of plant species that could be developed as crops or companion plants in such systems. This review is based upon a survey from an extensive dataset collected in Romania over the last sixty years to record the nectar production of 153 weedy species. While there was considerable variation among these plants, we found that the melliferous potential of such large families as the Brassicaceae was low, that of the Apiaceae, Asteraceae and Fabaceae at an intermediate level, and that of the lamiaceae and Boraginaceae the highest. High nectariferous potential was found to be an important feature of perennial ruderal species. Within the main flowering season, perennials provided much more nectar than annuals. These results could help to develop new agricultural practices more compatible with honey bee colony survival and honey production, as some of these plant species could provide a solution to enable agriculture and beekeeping to coexist in a sustainable way.