Ecotypes are groups of the same species that are native to different geographic regions and vary in physical characteristics. This is a result of evolution and will often exhibit local adaptation. Two ecotypes of Monarda fistulosa (Lamiaceae) were investigated for evidence of chemical differences unique to each ecotype. The plants were grown using a common garden methodology where all seedlings were grown in identical conditions over the same time period. Monarda fistulosa was used in the study, as members of the Monarda genus have been shown to vary in the chemical signatures of their essential oils within a species. Using gas chromatography-mass spectrometry, the essential oil extracts of these two ecotypes showed seven compounds that were unique to the essential oil of one ecotype. Five out of the 12 significant compounds identified were found in both essential oil extracts from the two ecotypes. Due to the common garden design, the differences in chemical signatures that were observed in M. fistulosa are likely due to genetic differences. Future research should explore whether these compounds have evolved in response to local selective pressures.