The way you dry your herbs determines the quality of what you keep. Poorly dried herbs (too slow, too hot, too much light, or stored before completely dry) lose their volatile compounds, their color, and much of their medicinal value. Well-dried herbs, stored correctly, retain most of their medicine for a year or more. This is one of the most practical skills in the home apothecary, and it is worth understanding properly.
The Principles of Good Drying
Three things matter most: temperature (low enough to preserve volatile compounds), airflow (high enough to prevent mold and speed the drying process), and light exclusion (UV light degrades many plant compounds). For aromatic herbs, temperature is the most critical factor: the volatile oils that carry most of the aromatic nervine, antimicrobial, and carminative activity evaporate at relatively low temperatures, and any drying method that runs above 35 to 40 degrees Celsius for these herbs will significantly degrade the final product.
Air Drying
Air drying is the oldest and cheapest method, and for non-aromatic herbs (roots, bark, high-tannin herbs) it is completely adequate. Tie small bundles (no more than 4 to 5 stems, to ensure airflow throughout) and hang in a warm, dark, well-ventilated space. An airing cupboard, a dry garden shed with good airflow, or a warm barn are all appropriate locations. Most aerial herb parts air-dry completely in one to two weeks in warm conditions, longer in humid weather.
For aromatic herbs (lavender, lemon balm, chamomile, thyme), air drying works if the conditions are right (warm, dry, with good airflow) but is less reliable than a dehydrator because it is harder to control temperature and it takes longer, allowing more time for volatile compound evaporation.
Dehydrator Drying
A food dehydrator set at its lowest temperature setting (usually 35 to 40 degrees Celsius) with the fan running provides the most reliable and controllable drying conditions for medicinal herbs. Most aromatic herb material dries in four to eight hours. The result is consistently more aromatic and medicinally potent than air-dried herb of the same plant in typical home conditions, because the quick drying preserves volatile compounds before they can evaporate.
The investment in a basic dehydrator pays for itself quickly in quality improvement. The Herbalist Codex app has specific drying guidance for individual herbs where the method particularly matters.