The pickling process involves soaking cucumbers or other vegetables in a brine that softens them and gives them flavor. Pickles can be sweet, sour, mild or hot, as they take on the intense flavor of the spices and herbs you use during processing. Unless a recipe calls for powdered spices, most are in the form of seeds or leaves soaked in the brine and that retain their shape in the jars.
Pickling spices and herbs are combinations of many you may already have in your own spice collection. Basic blends include the characteristic yellow mustard seeds that are visible in the bottoms of the jars, along with celery and coriander seed, whole peppercorns and whole cloves. Depending upon the manufacturer, other blends may contain whole allspice berries, cinnamon sticks, dill seeds, fennel seeds and juniper berries. Any one of these spices can be overpowering on its own or in too large an amount, and if you choose to create your own blends, it's wise to use them sparingly until you know how they'll behave in your pickle brine.
The general rule is to use the spices and herbs called for in the recipe, and this varies greatly depending upon the type of pickles you're making. In their purist form, dill pickles contain very few spices, and get their intense flavor from fresh the fresh heads or seeds of the dill plant, garlic and whole peppercorns. Sweet pickles made with sugar, such as bread-and-butter pickles, make use of a greater variety of spices such as turmeric, a powder often used in curries. Pickling other vegetables, such as green beans, generally involves using many of the same spices and herbs used in pickling cucumbers. A basic blend suggested by Williams-Sonoma includes whole cloves and allspice, two choices that lend a warm spiciness; red pepper flakes for a little heat, the tanginess of mustard seeds and the flowery-herbal essence of crushed bay leaves.
There is no hard and fast rule as to what types of spices and herbs you can add to your pickles, and you can experiment with whatever suits your fancy. If you like your pickles with an extra bite, you can add hot peppers or pepper flakes, thin slices of ginger or slightly crushed whole garlic cloves. Fennel and anise seed impart a mild licorice flavor, cardamom adds a light lemony touch to the brine and the flavor of coriander is reminiscent of the cilantro plant from which the seeds are obtained.
Herb and spice blends and any other flavorings used to make pickles are normally incorporated into a pickling liquid made of vinegar and water, which is heated to release their flavors. For cold-pack or refrigerator pickles, the brine is sometimes poured over the vegetables and spices in the jars, or the brine and spices are heated together before being adding to the jars. Water-bath processing or long-term storage may alter their colors, but that just means that the pickles have absorbed much of their flavor.