Increases in agricultural intensification of farmland are associated with increased habitat fragmentation and decreased on-farm biodiversity. The establishment of field margin plantings is one of the more well-studied and effective methods of combatting these effects. However, this strategy remains unpopular with farmers, largely due to concerns about the role of agronomic weeds within these plantings. Firstly, farmers often lack the time and resources required to intensively manage weeds within the margin of the crop field, which is often recommended when establishing biodiversity plantings. Second, farmers have voiced concerns about the potential for these plantings to act as reservoirs for agronomically problematic weed species, or for the seeded species to act as weeds within the crop. This research aims to address these concerns. The first chapter of this thesis is a two-year, two field site study that assessed plant communities within existing three- and four-year-old field margin strips established with minimal weed control. Despite the notable presence of weeds, seeded species were still found within the margins, especially when plantings were established at high densities with mixes containing both wildflower and grass species. These results show that the presence of weeds within field margin plantings does not prevent them from increasing floral resource availability. The second chapter is a two-year, two field site study that compared weed communities within planted margins to conventionally managed margins. Compared to conventional methods of field margin management, plantings decreased weed density and had no effect on weed biomass. Overall, this study demonstrated that the establishment of field margin plantings does not increase weed pressure in the adjacent crop.