Heritage Field Notes · Category A
Air-drying herbs requires nothing more than a dry room, a bundle of twine, and patience. The USDA Bureau of Plant Industry documented the method in the 1930s. It works exactly the same today.
In 1939, the USDA Bureau of Plant Industry published "Drying and Storing Herbs and Spices," a practical guide aimed at rural households that grew their own herbs and wanted to preserve them through winter. The bulletin documented harvest timing, drying methods, storage conditions, and which herbs retained quality through drying versus which were best used fresh.
The subject was not trivial. Pre-World War II American households used herbs extensively — for cooking, for preservation, and for home remedies that filled the gap before antibiotics. The extension service had been documenting herb-drying practices for decades, and the 1939 bulletin was a synthesis of that accumulated knowledge.
The central technique — harvesting at peak volatile oil content, air-drying in small bundles, storing in airtight containers away from light — has not changed because the chemistry hasn't changed. Essential oils dissipate under heat and light. The methods that preserve them in 1939 preserve them today.
Primary Source
Drying and Storing Herbs and Spices
U.S. Department of Agriculture, Bureau of Plant Industry. Leaflet No. 162. Washington, D.C.: Government Printing Office, 1939.
Public domain — U.S. government work. Search the Internet Archive →
The Method
The bulletin's air-drying method works for most culinary herbs and requires nothing that isn't already available in any household with a garden.
Morning, after dew dries, before the day heats. For most herbs, just before or at first flowering — this is peak essential oil content. Cut cleanly with scissors or a sharp knife. Remove any diseased, damaged, or yellowing material immediately.
Group stems into small bundles — 5-10 stems, not more. Large bundles don't dry evenly and can mold in the center. Tie at the cut end with twine. Hang upside down in a warm, dry, well-ventilated location away from direct sunlight. An attic, a dry shed, or a spare room with good air circulation all work.
Drying time depends on the herb's moisture content, ambient humidity, and temperature. High-moisture herbs like basil and mint take longer than woody herbs like rosemary and thyme. The herbs are done when stems snap rather than bend and leaves crumble between the fingers. Check bundles periodically for mold, especially in humid conditions.
Strip leaves from stems directly into airtight containers — glass jars work best. Label with herb name and harvest date. Store in a cool, dark cabinet away from the stove. The bulletin recommended against storing herbs near heat sources, which accelerates volatile oil loss. Whole leaves retain quality longer than ground; grind as needed.
Which Herbs Work
Not all herbs dry equally well. The bulletin divided them into three categories based on their behavior during drying.
Dry excellently
Rosemary, thyme, oregano, marjoram, sage, bay, and lavender. These have high essential oil content and low moisture. They air-dry readily, retain strong flavor, and keep well for 1-2 years. The bulletin specifically recommended these for year-round use from summer harvests.
Also: savory, hyssop, fennel seeds, dill seeds, caraway
Dry acceptably
Mint, lemon balm, tarragon, and parsley. These have higher water content and require good air circulation to dry without molding. Flavor retention is good but not as complete as woody herbs. The bulletin recommended drying in smaller bundles and checking more frequently for signs of moisture.
Mint dried quickly retains better flavor; slow-dried mint can lose clarity
Use fresh or freeze
Basil, cilantro, and chervil. The bulletin noted that these lose most of their characteristic flavor when air-dried. Basil's primary compounds are particularly volatile. For these herbs, the bulletin recommended using fresh in season, making herb-infused oils or vinegars, or — though not in the 1939 text — freezing (chopped into ice cube trays with water or oil).
Modern addition: freezing in olive oil is highly effective for basil
What It Teaches
Herb drying is the simplest food preservation skill in the heritage catalog: no equipment, no special knowledge, no safety concerns, no processing time. It requires only a dry room, twine, and patience. The result is a spice cabinet filled from a kitchen garden at essentially zero cost.
From a resilience standpoint, the skill matters because culinary herbs make stored food palatable. A pantry full of rice, beans, and canned goods is nutritionally adequate but monotonous. Rosemary, thyme, sage, and oregano dried from a summer garden — each from a $3 plant that will produce for years — transform the same pantry into a kitchen.
The 1939 bulletin was addressing a household that grew herbs for both culinary and medicinal use, in an era when the two overlapped more than they do now. The medicinal applications documented there belong to a different article. The culinary application is straightforward: grow what you use, harvest at peak, dry correctly, and the spice cabinet fills itself.
Sources