Control over flowering time is important for successful horti- and floriculture and the ability to manipulate flowering time is an economically important goal in plant breeding. Flowering depends on environmental conditions and internal signals from the plant s genetic program. Knowledge about how external stimuli control flowering time is, therefore, of great importance for plant growers. This is especially important in the face of changing greenhouse growth conditions, regional and global climate changes and globally expanding production areas. The environmental stimuli are perceived by different plant parts and are integrated in the shoot by so call integrators. In the shoot apical meristem, the floral integrators activate the floral meristem genes, which are responsible for the switch to reproductive identity. The aim of the proposed research is: i) identification of external factors that affect flowering time, with the emphasis on root-derived (e.g nutrients), light quality and ambient temperature parameters, ii) identification of the signaling cascades involved. This research will provide information, methods, tools and genes that can be widely used in plant breeding and production programs.