My collection of herbs and spices is a bit larger than that found in the usual kitchen. Because so many of my recipes are dependent upon basic ingredients, flavor provides the variety my tastebuds occasionally crave.
The challenge with such a collection is using it, and using it often, so that replenishment is frequent enough to keep it fresh. Fortunately, I love flavors!
Dried herbs, kept air-tight in a cool (not the refrigerator), dark, dry place are really only at their best within six months to a year of being harvested and dried. If they look grey and powdery, it may be time to get fresh, or in smaller amounts. Herbs that are still in their leafy form will hold their flavor better than those ground into powder; just crush the dried leaves between your hands to release the flavor. Thyme and rosemary are my favorites.
Spices that are seeds also keep better in their whole form; you will need either a mortar-and-pestle or a spice grinder. When I make my 4-6 month stash of cumin, I first toast the seeds on a medium-hot cast iron frypan until they are faintly golden and fragrant, then cool them on a plate; then I run them through my old Moulinex coffee grinder a tablespoon at a time. Coriander seed also gets toasted and cooled, and then ground in my brass mortar with brass pestle; it’s usually in small amounts for a particular recipe. Peppercorns don’t always get toasted, and again are ground in the brass mortar. Mustard seed, black and brown, is used whole, toasting a bit before adding other ingredients.
Spices that are barks and roots are more challenging for me to deal with. I get cinnamon in stick form for soups, stews, and mulled drinks. Ground cinnamon I get from a specialty store so I can choose the type; the regular cinnamon in the grocers is fine for beef stews and soups. I have fresh ginger for most cooking, and ground organic ginger for everything else. Turmeric is always ground; I always put a little into the oil that fries onions.
Once you know the key spices for a food culture, you can stock your own spice chest, and travel the world in food!