Follow the directions provided with the dehydrator. Herbs are sufficiently dry when they are brittle and crumble easily. When the leaves are dry, separate them from their stems and package the leaves in rigid containers with tight fitting lids. To preserve full flavor, avoid crushing the leaves until you are ready to use them. Store dried herbs in a cool, dry place away from sunlight, moisture, and heat.
Many herbs can be keep for a year if stored properly.
For Further Reading Duke, J. A. 1985. Culinary Herbs, A Potpourri . New York, New York. Foster, Gertrude and Rosemary Louden. Park's Success With Herbs .