Always dry herbs as quickly as possible. Choose a warm, dry spot with good air flow. Avoid kitchens, where airborne grease will cling to plants. Choose a dry basement, spare room, barn or an airy closet. Darkness isn't necessary, but it does help retain flavour in culinary herbs and colour in dried flowers. If plant material isn't starting to dry in a few days, a little extra air circulation from a fan or air conditioner (set on “circulate,” not “cold”) can help. Just make sure the flow is gentle and indirect, and not too hot.
Drying on a flat screen
A piece of screening, elevated so that air can flow under it, is excellent for drying small-stemmed plants such as thyme, flower heads such as camomile, flower petals such as roses, and the decorative leaves of scented geraniums or lady's mantle. Larger-stemmed herbs, especially those being used for cooking, such as tarragon, can also be dried this way. Just strip the leaves from the stems first. Spread herbs or flowers in a single layer and cover them with a thin sheet of cheesecloth or paper towel to keep the dust away. Stir them daily, changing their position to make sure they dry evenly.
Drying upside down
Gathering stems together with elastic bands and suspending them with a piece of string from the ceiling or a clothes hanger is a common way of drying culinary and crafting herbs such as sage, rosemary and artemisias. Hanging herbs sometimes attract insects or dust particles. To avoid this, tie the bundles and slip them into paper bags before hanging them. Punch a few holes in the bags to encourage air flow. Keep the herb bundles small and loose; large, tight bundles may hinder air flow, distort the herb's shape or encourage mould. Select four to six stems per bundle.
A great choice for everlastings-flowers or herbs with stiff stems, such as lavender and yarrow-is to dry them in empty dry vases, jars or tin cans (avoid plastic, which encourages mould). Don't crowd the herbs. To keep them separate, fasten a piece of chicken wire over the top and poke the stems through the holes.
Oven drying must be done carefully. As with the screen method, the herbs are dried in a single layer. The trick is maintaining a low enough oven temperature (38°C/100°F) over two to six hours. Oven drying requires regular stirring and careful watching. If you begin to smell the herbs while they are in the oven, they are losing precious oils. A less labour-intensive option is a food dehydrator. Use the lowest setting and check the herbs often. Leafy herbs such as nettles and scented geraniums might dry in a few hours, while flower heads might take a day or two.
Herbs should be “cornflake crisp” when dry, which can take several weeks at room temperature (less with machine drying). Dried herbs should retain their colour. If they have turned brown or faded quite a bit, they were dried too rapidly or at too high a temperature and, in the case of culinary herbs, have lost a significant amount of flavour.
Avoid storing dried herbs in plastic bags or plastic containers-it invites mould and mildew. If you have room, you can leave delicate crafting herbs such as baby's breath to hang. Otherwise, store herbs in clear, covered glass jars and keep them in a cool, dark place. Replace dried culinary herbs annually.