A two year trial was conducted in the southern Po river valley (near Bologna), in order to define the optimum harvest stage for maize silage under various cropping conditions (water availability, hybrid earliness). Maximum green fodder yield was reached, for all treatments, at the milk stage, 20–22 days after flowering, with a whole plant DM content of about 20–21%. On the other hand, maximum DM yield was reached at 40–45 days after flowering at a whole plant DM content of 42% and 38% for maize grown on irrigated and unirrigated land, respectively. Differences between hybrids were only apparent in unirrigated conditions where between the early and late hybrids again a range from 42% to 38% in whole plant DM content was observed, but with a delay of about a week for the former. Forage chemical composition, determined for the irrigated crop only, generally improved with the delay in harvest, mainly because of a reduction in crude fibre and an increase in N-free extract. In order to study the effects of harvest stage, i.e. of forage DM content, on the storage process, the experiments conducted during the last ten years at the “Centro Conservazione Foraggi” were elaborated. With the delay in harvesting the DM storage losses and the maize silage acid content decreased linearly, whereas the pH value increased. For high moisture grain and ear, except for the non-significance of DM losses, the same trend was recorded. The results of this research, finally, indicate the advantage of harvesting at the maximum crop yield stage, therefore after dough ripeness.