Bumblebees are important pollinators that provide vital ecosystem services. Unfortunately, they are negatively impacted by human factors such as climate change and agricultural intensification. Therefore, farmers are encouraged to implement measures to increase biodiversity. Planting flowering plants in fallows has been identified as a way to enhance pollinator diversity in agricultural landscapes, but further research is needed to determine if their effects are sufficient for pollinator survival. The aim of this study was to investigate whether flowering fallows can influence bumblebee growth and foraging behaviour. Colonies of buff-tailed bumblebees were placed near fields of Faba beans, with half of them located adjacent to flowering fallows. The bumblebee colonies were weighed, and their activity and pollen diversity were assessed through regular observations. The results showed no significant differences in bumblebee growth between the different fields. Only the fields with flowering fallows showed correlations between weight and activity in the colonies. Although there was a difference in pollen diversity, it did not contribute to a difference in weight gain, suggesting that other factors influenced bumblebee colony growth in the experiment. The bumblebees in both fields had similar access to flowering Faba beans, which may be a contributing factor to their growth since bumblebees rely on abundant pollen in the early stages of their life cycle. The short flowering period of Faba beans suggests that the flowering fallows could be an important resource later in the season. The findings of this report could enhance our understanding of bumblebee dynamics in the Swedish agricultural landscape and emphasize the importance of research on pollination measures.