I'll try and dig up the sources, but I did a little research on this a little while ago and the common idea was 2-3 months in air tight storage. I have stored cracked grain for two months and it worked fine. I'm getting a grain mill this weekend as it seems most of the experienced brewers on the forum recomend freshly milled grain. I noticed that it smells best when cracked fresh and after two months the fresh smell had faded a little.How long if it was cracked?