Warmth is one of the main factor driving germination and emergence processes. It is possible to determine the beginning and dynamic of emergence of weed species by summarizing growing degree days (GDD), which is used with the development of predictive emrgence models. Most of the weed species is characterized by inter-population variability which is manifested through different stages of dormancy, germination and weed emergence among different populations of the same weed species. Inter-population variability makes interpolation of foreign modeling weed emergence difficult for our agricultural domain. The aim of this study was to compare the emergence of Croatian population of the weed Abutilon theophrasti with 11 populations of this species from nine European countries and the United States by doing the field trial. For each studied population objective was to determine the growing deegre days for air and soil units needed for beginning and duration of germination. The experiment was set up in the fall of 2013 at Maksimir experimental station of Faculty of Agriculture Zagreb. The scheme of the experiment was randomized block schedule with 4 repetitions. The results of this study proved the existence of variability among researched populations of weed species Abutilon theophrasti. The lowest growing deegre days required for the 50% of emergence of sown seeds (415.15 GDD) were found in the US (Iowa, Minnesota) populations, as well as in the Croatian population. A significant difference was determined in the growing degree days with the Croatian and Portuguese population, where Croatian population needed 272,8 GD for the first emergence, while the slowest emerging populations of Portugal needed 382,1 GD.