While there is no reliable average shelf life, checking them annually should serve your purpose.
Bottled herbs and spices are thoroughly dried, and most spoilage bacteria can’t live without water, so if the containers are tightly closed the herbs and spices should last indefinitely without actually spoiling.
Also, things that are completely dry can’t freeze; it’s the water in foods that freezes. So the frigidity of your cabinet is irrelevant as far as damage from freezing is concerned. In fact, low temperatures will extend their useful lives by slowing down the evaporation of aromatic compounds.
Dried spices do lose their potency over time, however.
In fresh, undried herbs, the essential oils are contained in a variety of locations within the leaves, such as in inter-cellular cavities, specialized oil cells, oil or resin ducts, glands. or hairs. But because the cell structure is broken down in the drying process, the essential oils are closer to the surface, from where they can more readily escape.
Do the sniff test the next time you leave for the season: Crumble a bit of each one between your fingers, and if it doesn’t smell as strong as it did the preceding summer, make a note to bring a replacement on your return.
