During winter, dormant flower buds experience prolonged cold-exposure which results in bud break during spring and subsequent flowering. If floral buds get lost by freezing during winter, then the plants will not produce flowers. In contrast, remontant Hydrangea cultivars produce continuously flowers during the growing season also under non-inductive conditions. We hypothesize that in remontant Hydrangea a floral promoter gene is out-of-control. In this project, we will identify flowering genes of Hydrangea that control floral induction under low temperature and independently under short-day conditions. Following, we will compare the expression of these flowering genes in remontant and non-remontant Hydrangea cultivars to identify the genes that control remontant flowering.