Whether you have your own herb bed in the back yard, or gather plants in the wild for your herbal medicine chest, unless you properly dry and store them, you labor in vain. Most herbalists recommend air drying herbs to preserve their volatile oils. However, living in a humid area prevents me from simply hanging the plants up to dry. Therefore, I prefer using the oven or a food dehydrator.
The aerial parts of a plant are those that grow above the ground. That would include stems, leaves, flowers, seeds, or fruit. Generally, these are gathered in the spring and summer when the plant is putting all of its energy into flowering and producing fruit. These are the most delicate parts of the plant and are more easily burned in the oven, so keep a watchful eye.
Rinse the plant material in cool water and pat dry on a thick towel. Spread in a single layer on a cookie sheet.
Preheat the oven to 200 degrees. When it reaches the correct temperature, turn it off and insert the cookie sheet. The herbs will dry as the oven cools. After 20 minutes, check on them. If they are not yet dry, and if the oven has cooled, turn it on again. Make sure you turn it off once it reaches 200 degrees. If you do not turn off the oven, you will need to constantly check the herbs and turn them to keep them from burning. I have had much more success with this method.
Roots, Rhizomes, or Tubers
These underground parts to the plant are best harvested in the autumn after the aerial parts have died back and the plant’s energies are returning to the roots. Dig a deep circle about 8 inches away from the stem and pry the root from the ground. Use a stiff brush to remove any loose soil and then scrub it thoroughly in warm water. Cut away any soft, bruised, or insect eaten sections. Slice the root with a sharp knife and spread the slices in a single layer on a cookie sheet.
Like with the aerial parts, preheat the oven to 200 degrees. When it reaches the correct temperature, turn it off and insert the cookie sheet. This time, leave the roots in the oven for 2-3 hours.
The best time to harvest bark is in the fall when the sap is falling. Never cut a ring around a trunk or branch as that will prevent the nutrients to rise past that ring and the tree or branch will die. Only cut bark off in strips along the length of a branch. It is best to harvest bark from the outer branches that may be pruned later on. Or, if you require a great deal of bark, cut off an entire branch and remove all the bark from it. Remove any insects, lichen, or moss from the bark and brush with a stiff brush to remove any dirt. Cut it into small pieces and lay out on a cookie sheet. Dry as you did the roots.
Many people prefer to freeze-dry their culinary herbs as it retains the color and flavor more than heat drying. To freeze-dry simply place an entire sprig of herb in a zipper-shut bag and place in the freezer. Frozen herbs crumble well when needed for the soup pot.
Storing your dried herbs
Once dry, you will want to properly store your herbs to retain the active constituents. Always place dried herbs in a dark, glass container in a cool place. Heat and light can cause them to spoil. Plastic and metal can cause contamination. Properly dried and stored, your herbs can last up to a year.