Ground spices typically retain their fragrance and flavor for about 6 months to 1 year. After this period, their potency diminishes significantly.
Ground spices lose their flavor and aroma over time due to oxidation and the evaporation of volatile oils. The rate at which this happens depends on several factors, including how the spices are stored and the quality of the spices when they were initially ground. Generally, whole spices retain their flavor longer than ground spices because they have less surface area exposed to air and light. Once ground, the increased surface area accelerates the degradation process. To maximize the shelf life of your ground spices, store them in airtight containers away from direct sunlight, heat, and moisture. A cool, dark pantry is an ideal location. Regularly check your spices for potency by smelling them; if the aroma is weak or nonexistent, it's time to replace them.
To test the freshness of your ground spices, rub a small amount between your fingers. If the aroma is weak or nonexistent, it's time to replace them. Consider buying whole spices and grinding them yourself as needed for the freshest flavor.