Horseweed is a North American indigenous plant species commonly found in Nebraska cropping systems. Horseweed management is challenging due to its prolific seed production, long distance seed dispersal via wind, competitiveness, and rapid evolution of herbicide resistance. Understanding horseweed emergence pattern across Nebraska can contribute to implementing effective and more sustainable tactics to minimize its impact on cropping systems. Field studies were conducted during the fall and spring from 2016 to 2018 in Lincoln (corn and soybean), North Platte (wheat stubble and soybean), and Scottsbluff (corn and fallow) to investigate the emergence pattern of horseweed accessions from Lincoln, North Platte, and Scottsbluff, NE. Results showed that most horseweed seedling emergence occurred in the fall (99%), and only a few seedlings emerged in the spring across locations, except in the wheat stubble experiment at North Platte where higher spring emergence was detected (3 to 22%). In four out of six experiments, the density of total emerged seedlings of each accession was greatest when established in their site of origin. Our results suggest that late fall and/or early spring is likely the best timing for horseweed management across Nebraska.