How to Store Rosemary: Fridge, Freezer and Drying, Checked Against the Sources

Skip the damp paper towels. America’s Test Kitchen classes rosemary as a hearty herb, which stores differently from soft ones like parsley and mint: keep it dry, in its package or an open zipper-lock bag in the fridge.¹ It also dries well, so drying is a good option, not a last resort, as long as you keep the heat low. And be wary of the “fresh for up to three weeks” home number you’ll see quoted. It doesn’t trace back to any source we could find.

At a glance

Keeping fresh rosemary in the refrigerator

Hearty herbs are adapted to dry conditions and take in moisture through their leaves, ATK explains, so keeping them dry matters. Its method for hearty herbs is simple: leave them in their original packaging or put them in an open zipper-lock bag, and refrigerate. That’s not the damp paper towel method you’ll often see recommended for rosemary. Damp towels are ATK’s method for delicate herbs, not hearty ones. In the same guide, a slim herb keeper with a vented lid kept herbs fresh longer than the other containers ATK tested.¹

The Government of Canada’s general advice for fresh herbs is to store them unwashed, trim the stalk ends, put them in a resealable plastic bag and keep them in the crisper for up to five days, then rinse them under cool running water when you use them.² ATK adds that hearty herbs don’t hold much grit and only need a quick rinse if they’re dusty.¹

Ethylene. Some herbs, like mint and parsley, are very sensitive to ethylene, UC Davis’s postharvest fact sheet on fresh culinary herbs says. Others, rosemary among them, are barely affected or don’t respond at all.³

How long it lasts.

These measure different things: commercial storage just above freezing at very high humidity, versus a home food-safety rule of thumb. Neither tested rosemary on its own. UC Davis also notes that herbs generally lose essential oil and aroma in storage.³

Freezing rosemary

Rosemary, like thyme, can be frozen on the stem, Penn State Extension says. Its general methods for herbs:

• Sprigs or leaves on a tray. Spread them in a single layer on a cookie sheet and freeze, then move them to a freezer bag so you can take out only what you need.
• Ice cubes. Half-fill an ice cube tray with water, put about a tablespoon of chopped herbs in each section, freeze, and top up with water the next day.
• In oil. Mix 1/3 to 1/2 cup of oil with 2 cups of chopped herbs and freeze in trays or small jars. Add oil only if the herbs are going in the freezer, Penn State says, and never keep herbs in oil at room temperature.⁴

Rinse and dry the herbs gently before freezing. Use frozen herbs in the same amounts as fresh, and add them to cooked dishes without thawing. Freezing makes the water in the leaves expand, so they’re limp when thawed and generally not pretty as garnishes.⁴ Penn State doesn’t give a freezing time on the tray, and we found no published number for how long frozen rosemary keeps its flavor. More detail is in can you freeze rosemary?

Drying rosemary

What drying costs you. Drying temperature makes a measurable difference to rosemary’s aroma. In a 2001 study, leaves dried in normal air at 50°C (122°F) lost some of their aroma compounds outright and others dropped below fresh levels. Leaves dried in dried air at 30°C (86°F) kept all the characteristic compounds close to fresh.⁶ A 2007 study of Sardinian rosemary and thyme found that losses of volatile compounds depended directly on drying temperature and time, and for rosemary, drying at 38°C (100°F) with low airflow prevented the loss.⁹ Both point the same way: low and slow keeps more of rosemary’s aroma.

Air-drying. NCHFP names rosemary, along with sage, thyme, summer savory and parsley, as one of the sturdy herbs that are easiest to dry without a dehydrator: tie them into small bundles and hang them. Penn State wants a dry spot with good airflow, away from the sink, stove or dishwasher, and suggests a paper bag with holes punched in it to keep dust off.¹⁰

Dehydrator.

The 90°F starting setting you’ll often see is below both ranges. The low end of these ranges, 95°F, is 35°C, close to the 30°C and 38°C conditions that kept rosemary’s aroma in the studies above.

Oven. NCHFP describes drying herbs in a very cool oven, and says the light of an electric oven or the pilot light of a gas one gives enough heat for overnight drying.⁵ Penn State doesn’t recommend oven drying, saying even the lowest temperature destroys much of the flavor. If you do it, go no higher than 180°F (82°C), for 3 to 4 hours, door open.¹⁰ We found no source for drying rosemary at a 125°F oven setting or for a drying time of “a couple of days”.

Microwave. ATK’s method for hearty herbs: a single layer between two paper towels, 1 to 3 minutes on high, until the leaves are brittle and fall easily off the stems.¹ Penn State’s general method is to start with 1 minute, mix every 30 seconds and keep checking, about 2 to 3 minutes per cup. Penn State warns that the paper towels can catch fire if there’s too little in the microwave, and that a microwave of 1,000 watts or more may heat too fast.¹⁰ Neither drying study above tested a microwave.

Done when. Herbs are dry when they crumble and the stems break when you bend them. More detail is in how to dry rosemary.

Storing dried rosemary

Keep it in airtight containers somewhere cool, dry and dark. Leave the needles whole and crush them as you cook. Whole herbs hold their oils and flavor longer. Air, light, moisture and heat all speed up flavor and color loss. If you keep dried herbs in the fridge or freezer, let the container warm up before you open it, since condensation can form when a cold container meets a warm kitchen.¹⁰

McCormick is the only one that names rosemary, and it’s a spice company’s guidance for its own kind of product, not a measurement. Don’t average these. McCormick defines shelf life as how long spices stay most aromatic,⁷ so these are quality windows, not safety dates. To check, crumble a little and smell it.

Using dried rosemary. ATK found dried rosemary held up reasonably well in recipes with fairly long cooking times, more than 20 minutes, and a good amount of liquid. Ratio (Attributed): ATK found 1 part dried to 3 parts fresh came closest on flavor.¹⁴ See dried rosemary vs fresh.

Rosemary in oil

Rosemary-infused oil is a popular kitchen project, and it carries a botulism risk. Herbs are low-acid foods that can carry Clostridium botulinum, Oregon State University Extension explains, and oil creates an oxygen-free environment. For fresh herbs in oil made at home, it says to refrigerate and use within 4 days, or freeze.⁸ Penn State gives 2 to 4 days refrigerated for oils made with fresh herbs.¹⁵ For oils made with dried herbs, the two disagree:

We haven’t picked between them. Oregon State’s rule is the more cautious one.

Not yet measured

• How long fresh rosemary keeps in a home refrigerator, measured on rosemary.
• Whether damp towels or a dry bag keeps rosemary longer at home (ATK’s advice is to keep hearty herbs dry, but we found no published head-to-head test on rosemary).
• How long frozen rosemary keeps its flavor.
• A shelf life for dried rosemary measured on rosemary.

Related

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• Dried rosemary vs fresh
• Can you freeze rosemary?
• How to dry rosemary
• Cooking with rosemary
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• Rosemary substitutes
• Too much rosemary
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