Drying Herbs With a Food Dehydrator

Rosemary: fresh and dried
Getty Images/Donald Erickson
  • 01 of 06

    Types of Home Food Dehydrators

    Excalibur Food Dehydrator
    © Excalibur, used with permission.

    If you live in a climate of eternal sunshine, preserving food by drying is virtually effortless. But if you live elsewhere, or want greater convenience, you should consider a home food dehydrator.

    Home food dehydrators fall into two categories—those with stackable trays and those constructed of a rigid box with removable shelves. Size may be a determining factor in your choice. Most dehydrators fit on a countertop, but some larger models are free-standing and require more space. Some models have...MORE base-mounted fans that move hot air vertically, while others have a rear-mounted fan for moving air horizontally. Others use convection drying and have no fan at all.

    Stackable Dehydrator Units

    While these models may stack as high as 30 inches, they have a small footprint and consume little counter space. They also provide the least expensive way to get started with food dehydrating. However, they all share one big limitation—uneven heat distribution in the stack means that the trays closest to the heating element and fan dry much faster than those at the top of the stack. Diligent tray rotation is critical, especially if very fleshy foods are being dried. And while they are perfectly suitable for drying herbs, fruits, vegetables, fruit leathers, and jerky, these machines cannot readily be adapted for any of the other uses that the box-and-shelf models can claim.

    Box-and-Shelf Dehydrator Units

    Some of the box-and-shelf dehydrator units position the heat source and fan at the back of the shelves instead of beneath them. Hot air blowing across the shelves eliminates the bothersome need for tray rotation that hinders the stackable units. Some large models are big enough for other uses with some shelves removed, such as leavening bread, culturing yogurt, or drying bulky items.

    Other box-and-shelf designs rely on convection drying rather than a fan. Heat generated by a heating element mounted at the base of the box rises through the trays to dry the food. A benefit of convection drying is that it eliminates the possibility of contaminating foods with dirt particles that a fan may suck into a dehydrator. However, placing a fan-powered dehydrator in a clean space prevents that potential problem.

    Convection heating allows silent operation and less use of electricity. It is good for drying herbs, but it takes twice as long as fan models to dry bulky, moisture-laden foods such as tomatoes and peaches. The longer the drying time (especially during periods of high humidity), the more the dried product's flavor and shelf life will be reduced.

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  • 02 of 06

    Harvest and Prepare the Herbs

    Mint leaves being prepared for drying
    ©2008, A. Jeanroy, Licensed to About.com

    A dehydrator can be used with nearly all herbs but is especially good for herbs such as basil, oregano, tarragon, lemon balm, and mints. These herbs have a high moisture content and they often mold if they are not dried quickly in a dehydrator or some other method. 

    Herbs are best harvested just before the first flowers open when the buds are full. Gather them in the morning just after the dew has evaporated. Rinse the ​herbs in cool water and shake them gently to remove moisture. Don't rub...MORE them dry, as this bruises the leaves. Discard any leaves with spots or deformities.  

    As you prepare herb leaves for the dehydrator, begin by removing any long stems and damaged or bruised leaves. But it's fine to leave a bit of stem near the leaves as they go into the dehydrator. This can be a time saver when you are busy trying to harvest the entire fall garden. It also prevents bruising or damaging the leaves, which will reduce their quality when dried. After dehydration is complete, you can separate the leaves from the bits of stem before storing. 

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  • 03 of 06

    Place in a Single Layer on the Dehydrator Tray

    Dehydrator tray of mint leaves
    ©2008, A. Jeanroy, Licensed to About.com

    After rinsing with cool water and shaking the leaves dry, place the herb leaves in a single layer on the dehydrator tray. The leaves will dry more evenly. You may need to cover the dehydrator tray with a fine screen to prevent herbs from falling down into the bottom of the appliance.

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  • 04 of 06

    Remove Tray Above for Good Airflow

    Remove tray for better airflow
    ©2008, A. Jeanroy, Licensed to About.com

    To allow space for the larger leaves, you may want to remove some of the trays. It is important that all leaves receive plenty of air circulation, so remove any trays that aren't necessary. 

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  • 05 of 06

    Dry on the Lowest Setting Possible

    Dry on lowest setting
    ©2008, A. Jeanroy, Licensed to About.com

    For the best flavor, dry herbs on the lowest setting possible. If your dehydrator does not have a thermostat option, use the shortest period of time possible and check on the herbs often. A suggested temperature is 95 F to 115 F, but in conditions of high humidity, you may need to use 125 F. Typical drying time is one to four hours.

    Herbs are dry when the leaves crumble and the stems break when you bend them. 

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  • 06 of 06

    Store the Dried Herbs

    Crumble dried herbs
    ©2008, A.Jeanroy, Licensed to About.com

    If possible, it is always best to store dried herbs as whole leaves, as this best preserves their aroma and flavor. Then you can crush them immediately before using them. The one exception is where the herbs will be blended for use in teas—here, it's more convenient to crush the herbs immediately after drying, before storing them. 

    Store your dried herbs in an airtight container and keep it in a cool, dark, dry location. Any light or warmth will lead to faster deterioration, so avoid the urge...MORE to display dried herbs in the open. For best flavor, use the herbs within six months to one year.