Spices never actually go "off", but they do lose their potency and flavor over time, so there isn't much point using old spice in our cooking (leave that to the old men). Generally, whole spices stay fresh for about 4 years, ground spices for 3-4 years, and dried and leafy herbs for about 1year. The easy way to check? Sniff your stock. If you can't smell them, you won't be able to taste them.