Flowering time of wheat (Triticum aestivum L.) is a critical determinant of grain yield. Frost, drought and heat stresses from either overly early or overly late flowering can inflict significant yield penalties. The ability to predict time of flowering from different sowing dates for diverse cultivars across environments in Australia is important for maintaining yield as autumn rainfall events become less reliable. However, currently there are no models that can accurately do this when new cultivars are released. Two major Photoperiod1 and three Vernalisation1 development genes, with alleles identified by molecular markers, are known to be important in regulating phasic development and therefore time to anthesis, in response to the environmental factors of temperature and photoperiod. Allelic information from molecular markers has been used to parameterise models that could predict flowering time, but it is uncertain how much variation in flowering time can be explained by different alleles of the five major genes.