A. There are several different ways to preserve herbs - air drying, screen drying oven drying, seed heads and freezing.
Harvesting for drying: Most culinary herbs are harvested for drying just before they flower. At this time the aromatic oils are most concentrated. Pick the hers in the morning after the dew has dried but before the sun is hot. Use a sharp knife or shears, and avoid crushing or bruising the fragile foliage as this releases valuable oils. Once the herbs have been cut, wash them and gently shake off the excess water or pat dry with paper towels. Drying herbs involves exposing the foliage, flowers, or seeds to warm, dry air in such a manner as to not destroy the aromatic oils.
Air drying: Simply cut sprays, tie the ends of the stems together in small bunches and hang upside down in a well-ventilated room out of direct sunlight.
If the herbs are likely to catch dust, place them inside paper bags. Gather the bag closed at the top. Cut slits or holes in the bag to let the moisture escape. Sage, Rosemary and lemon balm dry well by hanging. This method takes from one to three weeks.
Screen drying: Spread the herbs in a single layer on a frame stretched with muslin, old nylons or old stockings. This method is ideal for summer savory and thyme that have leaves too small to handle individually. This also works with herbs with fleshy leaves. Pull these from the stems and spread so that the leaves are not touching. This method takes about one week, depending of the moisture content of the herbs, temperature and humidity. They are ready when the leaves are crisp and brittle.
Seed Heads: Herbs such as: anise, caraway, dill, fennel and coriander are harvested as soon as the seeds ripen and turn brown but before they scatter. Wait for a warm sunny day after the dew are dried. Put the seed heads in paper bags, tie the stalks in bunches with the heads in the bag. As with air drying, gather the bag at the top, cut slits to let the moisture escape. This can sometimes take up to six weeks.
Freezing: Of all the methods for preserving herbs, the best way, I my estimation is freezing. Gather the hers before the hot sun has robbed them of their freshness. Wash in cool water, shake or pat dry and place in plastic freezer bags. Label, date. Basil, burnet, chives, dill, fennel, parsley and tarragon freeze well. Herbs can be minced or frozen whole. If you cook a lot with olive oil, chop the herbs, mix with the oil, put in ice trays. When frozen, place in plastic, label and date. This way you can add the whole cube to different dishes. Oh! Mama Mia!!
Of course chopped herbs can be frozen in ice trays filled with water. In any method you use, remember to label and date. Most herbs need replacing after one year. Rosemary, thyme and sage usually last longer.