The life cycle of A. absinthium has been reported by Wrage and Kinch (1973). Growth begins in late April, and new plants are 4-12 inches tall by mid-May. Flowering begins in late July to early August. During late fall, the above-ground portion of the plant dies. Seedlings may emerge at any time from late spring to early fall (Wrage and Kinch 1973). Seedlings may be unnoticed for some time as they are low with small leaves before the upright flowering stems emerge (Wrage and Kinch 1973, Mitich 1975). Seed dispersal can be aided by running water, and root fragments carried by machinery may extend infestations in cultivated areas (Molberg 1976).
Allelopathy has been demonstrated in A. absinthium. Volatile emanations from the leaves of absinth completely prevented germination in wheat (Triticum triticale), and inhibited seedling growth in wheat, hoary cress (Cardaria draba), and common flax (Linum usitatissimums), whereas seedling growth on white mustard (Sinapis alba) was markedly stimulated.
Extracts made from the leaves of A. absinthium prevented germination of all four test species, and extracts of roots prevented germination of wheat and reduced root and shoot elongation in the other three species by 53-85% (Chirca and Fabian 1973).