SERRISTE is a decision support system that generates a suitable daily climatic set-points for greenhouse tomatoes planted in autumn. Scientific and expert knowledge about climate management has been analyzed and formalized in terms of constraints. These constraints express the acceptable values for each variable and the linkage that the biological and physical processes imply between some of these variables. SERRISTE has been tested in the main tomato production areas of France and has demonstrated its ability to operate a greenhouse as with the same results as local experts, but at a lower cost.