The dataset contains the density (plants/m²) of 7 weed species (Alopecurus myosuroides, Chenopodium album, Solanum nigrum, Polygonum convolvulus, Aethusa cynapium, Galium aparine, Polygonum aviculare) observed in 90 zones (10 fields x 9 sub-plots per field) over 17 years (2000-2017), in the integrated weed management cropping system experiment of the Dijon (FR) INRAE experimental farm. Weed density was assessed with four 0.36m² quadrats per zone (here averaged), 1 to 5 times per crop season but the dataset contains only the latest weed counting, which was carried out around crop flowering. Thus, 90% of the data represents weed counts made after weeding operations (the remaining 10% in absence of weed control the given year). These seven species represent the most common weeds of the study site, and differ according to their germination period and seed production potential.