Preserving Herbs by Donna Duffy

Photo courtesy herb gardening.com

One of the joys of summer cuisine is the addition of fresh herbs. Fresh herbs are showing up at the Farmers Markets, and many are ready to harvest in home gardens. As a general rule, herbs grown for their leaves should be harvested before they flower. For most herbs, the best time to pick is early in the morning just as the dew evaporates, but before the heat of the day.  Herbs can be used fresh from the garden or dried and enjoyed later. Following are tips for preserving and storing herbs.

Fresh and dried oregano, photo courtesy theepicentre.com

Drying Herbs

Drying is the traditional method for preserving herbs. To minimize wilting and maximize flavor, gather herbs in the morning of a dry day, just after dew has evaporated. Rinse thoroughly and dry with paper towels. Because many herbs look alike when dry, label them before you dry them. Herbs are dry when they are crispy, crumble easily, and stems break. Sun drying is not recommended because of the potential for insect infestation and loss of flavor and color. 

Food Dehydrator

Drying herbs with a commercial food dehydrator typically allows for better control of temperature within the recommended temperature range. Arrange herbs on drying trays in single layers; good air circulation between trays is important. The National Center for Home Food Preservation recommends pre-heating the dehydrator with the thermostat set to 95 º F to 115 º F. Check your dehydrator instruction booklet for specific details. 

Gas or Electric Oven

The oven light of an electric range or the pilot light of a gas range may furnish enough heat for overnight drying of herbs. Place single layer of herbs on oven-safe trays.

Microwave Oven

Drying in a microwave oven can be a good option for small amounts of herbs and appears to be the best drying method for reducing microbial contamination of herb leaves. Check the microwave oven owner’s manual for specific herb drying directions. Make sure herbs are thoroughly dry before placing in the microwave oven so that residual water does not cause the herbs to cook instead of dry. To dry, place a single layer of herbs between two paper towels on a microwave-safe plate. Place a ½ cup of water in 1 cup measure next to plate of herbs.

Some herbs, such as basil, should be dried on the microwave ovens ‘low’ setting. It is important to stop every 15 seconds to check the herbs and periodically turn them over. 

Air Drying

Air drying is the least expensive method but offers the least amount of consistency in drying and the greatest opportunity for contamination with bacteria or dust. Tie two to three sprigs of fresh herbs at the base of stems with twine and hang away from direct sunlight at room temperature or lay on cheesecloth stretched on frames or netting screens. 

Storing Dried Herbs

Dried herbs should be stored in a cool, dry place and most will keep well for up to a year. Their strength can be judged by their aroma. Dried herbs can be stored whole or crushed, but whole herbs retain their flavor longer. To ensure optimum quality, store in rigid, opaque containers with airtight seals. Choose ceramic jars or darkened glass containers to help protect the herbs against light deterioration. Make sure herb leaves are completely dry to prevent mold growth during storage. Label all storage containers with the herb’s name and date. 

Freezing Herbs

Quick-frozen herbs will keep up to one year in the freezer if well packaged. To tray-freeze herbs, wash them, then drain and pat dry. Strip leaves off stems, spread leaves in a single layer on a cookie sheet; place in freezer for at least 30 minutes. Place the frozen leaves in a freezer bag. Label with herb’s name, date, and return to freezer for use as needed. 

For more information, check out CSU Extension’s Fact Sheet Herbs: Preserving and Using.