Low-growing and aromatic evergreen herbs reaching only 1 to 18 inches tall, thymes (Thymus spp.) vary in hardiness from U.S. Department of Agriculture plant hardiness zones 3 through 11. The classic culinary type is the 12-inch-tall common thyme (Thymus vulgaris, USDA zones 5 through 9), whose miniscule, two-lipped, white, pink or lilac flowers appear from early summer to midsummer. Its 1/2-inch small and pointed gray-green leaves make the herb easy to dry and store.
Give your thyme plants a spot in poor and well-draining ground -- with a neutral pH near 7.0 -- in full sun, as too much water or too fertile a soil can have a detrimental effect on their flavor and fragrance. A mulch of gravel will help keep mud from spattering onto their foliage. It’s a good idea to cover your thyme plants with evergreen boughs for winter protection in cold climates, and to prune off the top one-third of the plants in early spring to force them to bush out more.
For the strongest flavor, harvest thyme just before the plants bloom. Wait until after the dew has dried in the morning to cut the herb, snipping off the top two-thirds of each shoot. Avoid cutting back into the plants' woody sections that no longer have leaves, as those aren’t likely to leaf out again. After taking the harvested shoots into the house, swish them in a bowl of water to clean off any dirt sticking to their leaves. Shake off the droplets of water and lay the thyme on dishtowels or paper towels until the moisture left by the washing has dried.
You have several options open to you for drying thyme. If you have an airy unused room -- such as an attic or shed -- available, you can tie the thyme sprigs into small bundles and hang them upside down from horizontal lines until their leaves feel dry and brittle. Alternatively, you can lay window screens across sawhorses, chair backs or other supports and dry the herb atop the screens. Air drying may require several days. To speed up the process, spread the thyme sprigs on the trays of a dehydrator and heat them to between 90 and 100 degrees Fahrenheit. The thyme will dry in about 24 hours in a dehydrator. For even faster results, place the stems in a single layer between paper towels and microwave them on high. Run the microwave for only 60 seconds at first. If the leaves aren’t brittle yet, keep adding another 30 seconds of time until they are, allowing them to cool before you attempt to handle them.
Once the thyme sprigs are completely dry, remove the leaves from the stems and discard the stems. Store the leaves in small, screw-top glass jars in a dry and dark area such as a kitchen cupboard.