Weed management remains a high priority for organic farmers, whose fieldsgenerally have higher weed density and species diversity than those of theirconventional counterparts. We explored whether variability in farmerknowledge and perceptions of weeds and weed management practices werepredictive of variability in on-farm weed seedbanks on 23 organic farms innorthern New England. We interviewed farmers and transcribed and codedinterviews to quantify their emphasis on concepts regarding knowledge ofecological weed management, the perceived risks and benefits of weeds, andthe perceived risks and benefits of weed management practices. Tocharacterize on-farm weed seedbanks, we collected soil samples from fivefields at each farm (115 fields total) and measured germinable weed seeddensity. Mean weed seed density per farm ranged from 2,775 seeds m−2 to 24,678 seeds m−2 to a soil depth of 10 cm.Farmers most often reported hairy galinsoga and crabgrass species (Digitaria spp.) as their most problematic weeds. Theproportion of the sum of these two most problematic weeds in each farm'sseedbank ranged from 1 to 73% of total weed seed density. Farmer knowledgeand perceptions were predictive of total seed density, species richness, andproportion of hairy galinsoga and crabgrass species. Low seed densities wereassociated with farmers who most often discussed risks of weeds, benefits ofcritical weed-free management practices, and learning from their ownexperience. These farmers also exhibited greater knowledge of managing theweed seedbank and greater understanding of the importance of a long-termstrategy. Targeted education focusing on this set of knowledge and beliefscould potentially lead to improved application and success of ecologicalweed management in the future, thus decreasing labor costs and timenecessary for farmers to manage weeds.