Vernalization is known to promote flowering in Arabidopsis thaliana by inhibiting the expression of a strong repressor: FLOWERING LOCUS C (FLC). The recent cloning of an FLC-LIKE gene in sugar beet (Beta vulgaris; BvFL1) and – here – in root chicory (Cichorium intybus; CiFL1) suggests the conservation of FLC biological function during evolution of eudicots. Hence physiological questions that remain difficult to address in Arabidopsis can be studied in other species. We investigated the correlation between CiFL1 expression and plant-age dependent responsiveness to vernalization. We also studied the effect of post-vernalization growing temperature, which can stabilize or erase the vernalized state.