Foodgoat only uses dried parsley when he has run out of fresh parsley, a rare occurrence since he has taken to keeping bunches of parsley leaves in the freezer.
Although he still had plenty left, Foodgoat decided to pick up a new batch (cost: $2 for an ounce) because he had had the old parsley for ... well, a long time.
As you can see, the fresh batch looks considerably better than the old batch. It's actually green. And smells like parsley. And tastes like parsley!
Although herbs and spices don't spoil in the same way or with the same speed that dairy products do, for example, they do lose their potency and flavor. And flavor is the whole point of herbs and spices.
If properly stored in a cool, dry, airtight place, whole spices can keep up to 4 years, ground spices up to 3 years, and dried herbs up to 1-2 years.
Yet this is something I always neglect to do. The last time I did, I found a spice jar that was at least 10 years old.
How can you tell if it's still good to go? Smell. If it still smells the way it's supposed to, you can probably still use it, although you might want to use more of it to overcome the decline in strength. Somewhat stale spices can also be revived by toasting lightly them in a skillet and using them right away.
If not, throw it out or compost it or donate it to your child's play ingredient shelf, and buy some fresh spices.