Believe it or not, spices do have a limited shelf life. This is not only true for fresh spices such as ginger, garlic, and lemon grass, but for dried spices as well. Whole spices can last for a year or longer. Once opened, ground spices only last from four to six months before their flavor lessens. One exception is dried mustard, which lasts for over a year.

Preground spices gradually lose their potency. Within six months, their strength has diminished significantly. You don't have to toss them out at exactly six months, but you may need to add an extra pinch or two (to taste). Replace spices when you notice that the aroma has weakened or the color has faded.