Drying herbs is a method of preservation. For success, the drying method should expose the herbs to the circulation of warm, dry air to allow evaporation of moisture.
1. Choose an ideal harvesting time. The ideal time is just before flower buds open and in the early morning after the dew has evaporated.
2. Collect the best leaves without bruising them.
3. Do NOT expose herbs to the sunlight as the herbs may lose their useful properties as well as color and flavour. In other words, after harvesting the herbs, do not leave them unattended in the sun, especially as a means of drying the herbs. For this reason, I like collecting herbs in a woven basket with a covering cloth.
4. Rinse the herbs under cool, running water and then shake off excess water
5. Whatever your dehydration method and apparatus, arrange the herbs to maximize air circulation. Temperatures need to be higher for more humid environments.
a. For air drying hardier herbs (like rosemary and thyme that are less likely to mold if drying does not occur very quickly), simply tie the stems into small bundles and hang them in warm, dry air.
b. For air drying tender herbs (like basil, tarragon and lemon balm that are likely to mold if drying does not occur quickly), suspend very small bundles inside a paper bag with holes along their sides. The advantage of the paper bag is that falling leaves will be caught at the bottom of the bag. This method can easily fail if individual leaves on stems do not receive sufficient air circulation.
c. For oven drying tender or hardy herbs (like mints and bay leaves). Pack single layers one leaf thick onto paper towels. Do not allow the leaves to make contact. Up to 4 other layers of paper towel and leaves can be stacked one atop the other. The only required heat source is the oven light or gas stove pilot light. The leaves may be dried this way overnight.
d. For microwaving small amounts of herbs. Spread the herbs onto paper towels so their leaves do not touch. Check and turn the herbs at 15- to 40-second intervals in the microwave until they are completely dry. The leaves will crumble when you rub them between your fingers. You may even stack layers of paper over each other. However, do this in moderation.
6. Dry the leaves until they are crispy.
7. Prepare the herbs for storage. This may involve crumbling the herbs between your fingers. You may also remove husks from seeds in this way before blowing away the husks.
8. Store the dried herbs in an airtight container. This will help to preserve the medicinal, color and fragrant properties.
9. When using herbs, dried herbs are roughly 3 to 4 times more potent than fresh ones. This should therefore be considered for adjusting recipe measurements.