How to Rehydrate Dried Herbs (and When Not To)

Recipe telling you to soak your dried herbs first? Most of the time you can skip it. Dried herbs soak up moisture from the dish they’re cooking in, and that’s how they release their flavor.¹ Where a head start helps is in quick-cooked dishes and food that isn’t cooked at all, and even there your best tool is usually fat or time, not a bowl of water. In one America’s Test Kitchen test, oil steeped with thyme held 10 times as much thymol as water did.

Quick answer

You’re making	What to do
Soup, stew, braise or simmered sauce	Add the dried herbs straight to the pot. Hardy dried herbs do best with more than 20 minutes of cooking and plenty of liquid.²
A quick sauté or pan sauce	Bloom the herbs in the hot oil or butter before the liquid goes in.³
Dressing, dip, marinade or herb butter	Mix the herbs in well ahead of serving so they have time to soften and flavor the food.¹
A garnish	Use fresh herbs. ATK says dried herbs used as a garnish can add an unpleasant texture.⁴
A recipe that says to soak them	Do it in a liquid the recipe uses, and keep the liquid (see below).⁵

Why dried herbs need moisture

Moisture hydrates a dried herb’s cells and makes them porous, America’s Test Kitchen (ATK) explains, which is part of why dried herbs do best in dishes with liquid. Rehydrating won’t turn a dried herb back into a fresh one, though. In ATK’s tests of fresh against dried herbs in 24 recipes, tasters preferred fresh in all but one, and they called dried herbs “dusty” and “stale.” ATK puts part of that down to oxidation during drying.²

Simmered dishes: add them to the pot

This is where dried herbs shine. ATK found that dried oregano, rosemary, sage and thyme did reasonably well in dishes cooked more than 20 minutes with a good amount of liquid.² A second ATK guide lists bay leaf, thyme, oregano, rosemary, marjoram and sage as working fine in moist dishes cooked at least 20 minutes, like chili or poultry stuffing.⁶

The delicate herbs are a different story. Basil, cilantro and other delicate herbs get much weaker once dried, ATK says,⁴ so no amount of simmering will make a jar of dried basil taste like fresh. See dried basil vs fresh.

When to add them. The sources don’t agree:

Source	Advice for dried herbs
Colorado State University Extension¹	Add near the beginning of cooking, to give the herbs time to rehydrate.
America’s Test Kitchen⁴	Add them at the same point you would add fresh herbs.
University of Delaware Extension⁷	In long-simmered dishes, add herbs during the last 45 minutes.
Spices Inc. (a spice merchant)⁵	Add dried herbs at least 20 minutes before cooking is complete; delicate herbs at the end.

None of the sources tested these timings against each other. For a pot that cooks for hours, Delaware’s last-45-minutes rule is the safe bet.

Quick dishes: bloom them in fat

For a dish that cooks only a few minutes, heating dried herbs briefly in oil or butter is the most useful thing you can do, and it’s the step with a measurement behind it. ATK steeped thyme in oil and in water at 200 degrees for 20 minutes and had both tested. The oil held 10 times as much thymol as the water.³ The main flavor compounds in many spices, and in herbs like thyme, rosemary, lavender, sage, savory and bay, are largely fat-soluble, ATK says.³ Its test page doesn’t say whether the thyme was fresh or dried.

How: warm the oil or butter over medium heat, add the crumbled herbs, stir briefly until fragrant, then add the liquid or other ingredients. Watch closely and go by smell.

Uncooked foods: give them time

Dried herbs in a dressing, dip, marinade or compound butter have nothing hot to wake them up. Herbs in uncooked foods like salad dressings, dips and fruit mixes need time to blend their flavors, Colorado State says, so add them as far ahead of serving as you can.¹ Mixing them into the oil, vinegar or other liquid first, before the thicker ingredients, works on the same idea.

Soaking in water: what one merchant says

Some recipes have you soak dried herbs in warm water and drain them. Spices Inc., a spice merchant, says don’t. Herbs have thin walls and rehydrate quickly in whatever moisture is in the dish, and soaking them in hot water pulls their volatile oils into the water, which then goes down the drain.⁵ We found no extension service or test kitchen that gives a soak time for culinary herbs. If a recipe insists, soak them in a little of a liquid the recipe already uses (stock, wine, lemon juice or vinegar) and add that liquid along with the herbs.

Crush them first

Whatever you’re making, crushing helps. Delaware suggests crushing dried herbs first to release some of their oils,⁷ and Spices Inc. recommends rubbing them between your hands as they go in.⁵

Safety: dried herbs in oil

Covering dried herbs with oil, for a dipping oil or a flavored oil, is about more than rehydrating. Oregon State University Extension says homemade mixtures of dried herbs in oil must be refrigerated and used within 4 days or frozen, because low-acid foods stored in oil create an oxygen-free environment where Clostridium botulinum can grow.⁸ Colorado State gives the same 4-day fridge limit for homemade herb-infused oils.¹ Those limits are about storing the mixture. The guidance doesn’t cover oil heated with herbs and used right away in cooking.

How much dried to use in place of fresh

Rehydrating doesn’t change how much dried herb you need, and the published conversions disagree:

Source	Dried for fresh
LSU AgCenter⁹	1 teaspoon crumbled dried for 1 tablespoon finely cut fresh
America’s Test Kitchen, tested²	1 part dried to 3 parts fresh came closest
America’s Test Kitchen, “Using Dried Herbs”⁶	Half the amount called for in the recipe

The first two are the same proportion (a tablespoon is 3 teaspoons). The third is a different number from the same publisher. Ratio (Method): use one third as much dried as fresh, then taste and add more. For herb-by-herb detail, see dried herbs vs fresh.

Not yet measured

How long dried herbs take to rehydrate fully in a simmering liquid, for any herb.
Whether a water soak loses measurably more flavor than adding herbs directly, outside one merchant’s explanation.
A tested blooming time for dried herbs (ATK’s blooming test used a 20-minute steep at 200 degrees).
Whether soaking in wine or vinegar changes a dried herb’s flavor differently from water.

Herbs: Preserving and Using, Fact Sheet 9.335, Colorado State University Extension. ccfruitandnuts.ucanr.edu · Reference work ↩ ↩² ↩³ ↩⁴ ↩⁵
Science: Substituting Dried Herbs for Fresh, America’s Test Kitchen. americastestkitchen.com · Publication ↩ ↩² ↩³ ↩⁴
Blooming in Oil for Flavor, America’s Test Kitchen. americastestkitchen.com · Publication ↩ ↩² ↩³
When You Should Actually Use Dried Herbs, America’s Test Kitchen. americastestkitchen.com · Publication ↩ ↩² ↩³
Spice Cabinet 101: Getting the Most Out of Your Dried Herbs, Spices Inc. spicesinc.com · Merchant ↩ ↩² ↩³ ↩⁴
Using Dried Herbs, America’s Test Kitchen. americastestkitchen.com · Publication ↩ ↩²
Using Herbs and Spices, University of Delaware Cooperative Extension. udel.edu · Reference work ↩ ↩²
Herbs and vegetables in oil, SP 50-701, Oregon State University Extension Service. extension.oregonstate.edu · Reference work ↩
Flavorful Herbs, LSU AgCenter. lsuagcenter.com · Reference work ↩

How to Rehydrate Dried Herbs: When You Need To, and the Better Ways to Wake Them Up