The GRDC National Phenology Initiative aims to deliver accurate cultivar and environment specific estimations of wheat and barley phenology to grain growers and their advisers. It will achieve this by improving and validating the APSIM Next Gen phenology routine and allowing cultivars to be parameterised using controlled environment data, molecular markers, single-nucleotide polymorphism genotypes (SNPs) or a combination of the above. Simulations will be validated against field data for a wide range of phenology phenotypes (the Australian Phenology Panel comprising 64 wheat and 32 barley genotypes) from diverse locations across the Australian wheat belt. Information will be delivered to growers via a web interface on the NVT website.