Achillea filipendulina is a ornamental plant with various biological and pharmaceutical properties. Essential oil (EO) yield and composition, polyphenolic content, antioxidant activity and anatomical traits were assessed during four developmental phases viz. five leaves appearance, sprouting, 50% and 100% flowering. The yield of EOs ranged from 0.22% to 0.78% at five leaves appearance stage and 100% ï¬owering stage, respectively. Samples collected at 100% flowering possessed the highest monoterpenes and the lowest sesquiterpenes derivatives compounds. 2,7-dimethyl-4(E),6-octadiene-2-ol was the most prominent component. The highest EO antioxidant activity was also observed at full-flowering stage. Also, 50% flowering stage contained the highest antioxidant capacity in comparison to the other phases. Finally, 50% flowering phase can be suggested as the optimal harvesting time for gaining high antioxidant capacity of phenolic extracts, while 100% flowering stage was more suitable in respect to favorite EO components and their antioxidant activity in this species.