Weeds are plants adapted to habitats modified by people and that often interfere with different human activities. These plants constitute an economically and ecologically relevant group because of their implications for agriculture. Because the agrestal weeds of the state of Colima, Mexico have been poorly documented, we surveyed these plants in commercial agricultural fields and plantations of the state, from February 2015 through May 2019. We surveyed 25 sites, each of about 1 ha, dedicated to cash-crops (blueberry, blackberry, coffee, maize, onion, jalapeño pepper, papaya, Mexican lime, and sugarcane). We found 222 weedy species (43 eudicots, 6 monocots, 2 magnoliids, 1 fern, and 1 liverwort), belonging to 53 families. The most species-rich families were Poaceae (29 species) and Asteraceae (25). A high percent of the weed flora was native (84.2%) and 15.8% alien. The most common species were Euphorbia hirta and Heliotropium procumbens. We found 21 endemic species and Manihot chlorosticta in the near threatened (NT) risk category of the IUCN. Also, we found that each crop tends to have a distinctive weed community, which in general appears to be determined by bioclimatic factors, principally temperature and precipitation.