How to Dry Herbs: Air-Drying vs Dehydrator vs Oven

How to Dry Herbs: The Three Methods Compared

To dry herbs, match the method to the leaf. Sturdy herbs such as rosemary, sage, thyme and parsley can hang in small bundles until they crumble, which may take up to a month. Moist, tender herbs such as basil, mint and tarragon mold when they dry slowly, so they do better in a dehydrator set to 95 to 115°F, where most batches finish in 1 to 4 hours. An oven works when it is all you have, held at its lowest setting and never above 180°F.

The table puts the three methods side by side, with the microwave added for very small batches.

Method	Temperature	Typical time	Suits	Main risk
Air-drying	Room air, out of sun	Up to a month	Rosemary, sage, thyme, summer savory, parsley	Mold in moist leaves or large bunches
Dehydrator	95 to 115°F, up to 125°F where humid	1 to 4 hours	Basil, mint, tarragon, lemon balm, oregano	Overheating on a fruit or jerky setting
Oven	Lowest setting, not above 180°F	3 to 4 hours, or overnight on the oven light alone	Any herb when nothing else is available	Cooked leaves, lost aroma
Microwave	High power	2 to 3 minutes per cup	Small quantities	Paper towels catching fire

Heat is the reason the methods rank this way. The flavor of an herb sits in volatile oils, and those oils leave the leaf along with the water when the temperature climbs. A dehydrator removes water quickly at a temperature barely above a hot summer day. An oven removes it at a temperature that also drives off oil.

When to Cut Herbs for Drying

Flavor in the jar starts with timing in the garden. The National Center for Home Food Preservation puts the best harvest point for most herbs just before the flowers first open, at what it calls the bursting bud stage. Cut in the early morning after the dew has evaporated, so the leaves are dry on the surface and have not yet wilted in the sun.

Penn State Extension advises leaving 4 to 6 inches of stem on the plant for later growth. Cut with a sharp blade so the stems are not crushed, a point covered in our guide to herb scissors for harvesting. Rinse the stems in cool water, shake off the excess, and discard bruised or soiled leaves. Herbs from a windowsill herb garden are handled the same way and usually need less washing.

Air-Drying: Small Bundles for Sturdy Herbs

Air-drying costs nothing and suits what the food preservation center calls the less tender herbs: rosemary, sage, thyme, summer savory and parsley. Tie the stems into small bundles with a rubber band, which tightens as the stems shrink, and hang them indoors, away from the sink, stove and dishwasher, where the air is damp. Sun drying is not recommended because the herbs lose flavor and color. Drying time depends on the room. University of Illinois Extension notes that it may take up to a month for herbs to dry completely this way.

Tender-leaf herbs are a different case. Basil, oregano, tarragon, lemon balm and the mints carry a high moisture content and will mold if they are not dried quickly. If you want to air-dry them anyway, use the paper bag method. Tear or punch holes in the sides of a paper bag, suspend one small bunch inside, close the top around the stems with a rubber band, and hang the bag where air currents pass through it. The bag catches any leaves and seeds that drop, and the small bunch matters because large amounts mold.

A second option for tender leaves is to strip the best leaves from the stems and dry them flat on paper towels, a method described under oven drying below.

Dehydrator: 95 to 115°F for 1 to 4 Hours

A dehydrator gives the most even result because it combines low heat with moving air. Preheat it with the thermostat set to 95 to 115°F. Penn State gives a slightly narrower window of 95 to 110°F, so the low end of the dial is the place to stay. In areas with higher humidity, temperatures as high as 125°F may be needed to finish the job.

Lay the rinsed herbs in a single layer on the trays. Drying times vary from 1 to 4 hours, so check the trays periodically. Thin leaves finish well before thick ones. This speed is what makes the dehydrator the best match for basil, mint and the other tender-leaf herbs that mold on a slow schedule, and it is the dependable choice in a humid house in any season.

The common mistake is leaving the machine on a setting meant for fruit or meat. Those settings run hotter than the herb range, and extra heat costs the leaves flavor, oil and color.

Oven Drying: The Backup Method

Extension sources are cool on oven drying. Penn State says it is generally not recommended because even the lowest temperature destroys much of the flavor, oil and color. Anyone who does use an oven should keep it at the lowest temperature, not above 180°F, for 3 to 4 hours with the door open. Illinois Extension describes the ideal oven drying temperature as 90 to 110°F, says the lowest setting with the door slightly open can often hold that level, and gives the same 3 to 4 hours.

There is a gentler version that works better. For mint, sage or bay, strip the leaves, lay them on a paper towel so they do not touch, cover them with another towel, and add more layers in the same way. Up to five layers can be dried at one time. Put the stack in a very cool oven. The oven light of an electric range or the pilot light of a gas range supplies enough heat to dry the leaves overnight, and leaves dried flat like this keep good color.

A microwave handles very small quantities. Penn State’s method is one layer of herbs between microwave-safe paper towels on high for 2 to 3 minutes per cup. Illinois suggests 1 to 3 minutes and checking every 30 seconds, turning the herbs so they dry evenly. Stay beside the microwave. Penn State warns that the paper towels can catch fire when the volume of herbs is too small.

How to Tell When Herbs Are Dry

Herbs are dry when the leaves are crispy and crumble easily between your fingers and the stems break when bent. A leaf that bends or feels leathery still holds water, and water in a closed jar means mold. Give it more time, whatever the clock says.

Check the jars often during storage. Clemson’s fact sheet favors glass because any moisture that collects on the inside is easy to see. Herbs affected by moisture that have not spoiled should be used at once or dried again and repackaged.

Storing Dried Herbs

Store dried herbs in airtight containers in a cool, dry, dark area. A cabinet away from the stove beats a rack above it. Keeping the leaves whole and crumbling them as you cook holds the oils in longer than crushing the batch up front.

Most dried herbs keep well for up to a year, and Clemson’s fact sheet gives a range of four months to a year for dried foods in general. Past that they are still usable but weaker. Dried herbs are usually 3 to 4 times stronger than fresh, so use 1/4 to 1/3 of the amount a recipe lists for fresh herbs. In kitchen terms that is about 1 teaspoon dried for 1 tablespoon fresh. Our fresh vs dried herb substitution guide covers the herbs that break this rule.

Some herbs dry poorly however carefully you do it. If your basil comes out dull, the plant is still producing, and you would rather keep cutting it fresh, see how to pinch basil to extend the harvest.