The induction of flowering is a central event in the life cycle of plants. When timed correctly, it helps ensure reproductive success, and therefore has adaptive and economic value: precocious flowering often results in reduced yield, both in biomass and fruits, whereas a delay in flowering can result in an increase of biomass. However, the latter is usually accompanied by reduced seed set or seed filling, limiting the use of late-flowering varieties in agronomics. Because of its importance, flowering is under the control of a complex genetic circuitry that integrates endogenous signals such as hormonal and carbohydrate status, and environmental signals such as temperature and light. Genetic analyses had initially suggested the existence of distinct, genetically defined pathways that regulate flowering in response to a specific input. Over the last several years, however, it has become apparent that many important flowering time genes are not regulated by single inputs, but rather integrate multiple, often contradictory signals to control the induction of flowering. I will discuss the effects of environmental stimuli in modulating chromatin features at the shoot apical meristem and in the leaf vasculature the expression of integrator genes to ensure that flowering commences under optimal conditions.