Food Preservation: Preserving Herbs—Freezing and Drying

Key facts about herbs:

• Herbs are fragrant plants, used primarily for flavoring food, perfume, and medicinal purposes.
• The flavor comes from the oils in the plant. Scratching, chopping, or grinding releases the flavor and aroma.
• Once harvested, fresh herbs have a relatively short life of only a few days in the refrigerator.

Why Preserve Herbs

Preserving herbs after the harvest is very quick and easy. The most common methods for preserving herbs are freezing and drying. Preserving herbs allows for seasonal use year-round and maintains flavor and nutrients. Drying is used for more delicate herbs like dill, while freezing is used for more hearty herbs such as thyme and rosemary.

Drying Herbs

Drying is the easiest method of preserving herbs. When moisture is removed from food, microorganisms that cause spoilage cannot grow, however, know that dehydration does not kill them entirely. The drying process also slows down the action of enzymes (substances naturally present in food that promote ripening), which helps dried herbs have a longer shelf life. When drying herbs at home, it is important to account for where you live and the current weather conditions. This is because low humidity promotes the drying process. If you live in the Midwest, or other regions that can have periods of higher humidity, keep in mind that humid conditions are not conducive to air drying.

Tips for Harvesting

• The best time to harvest herbs for drying is just before the flowers open, when they are in the bursting stage.
• Gather herbs early in the morning.
• For perennial herbs, cut no more than 1/3 of the plant’s height at a time.
• Herbs should not lie in the sun, because the sun’s rays can degrade their quality.
• Label the herbs when picked because many herbs look alike, especially after they are dried.

Tips for Drying Herbs:

• Rinse the herbs under cool running water and shake to remove excess moisture. 
• For all drying methods, it is important to monitor the temperature because high-heat environments can cause a lower quality end product.
• Herbs are dry when they crumble easily between your fingers, or when the stems break when bent. 
• Dried herbs can be kept for up to a year for best quality.
• Store dried herbs in an air-tight container, label with the name and the date packaged, and store in a cool, dry, dark area to protect their color and fragrance. 

Important Tip

Dried herbs are stronger than fresh herbs. Dried herbs are usually three to four times stronger than the fresh herbs, so use about 1/3 to 1/4 less.

How to Dry Herbs

1. Microwave Drying

Microwave drying is a fast method for drying herbs in small quantities. Layer herbs in a single layer on a microwave safe plate. Microwave drying varies, so please check the owner’s manual for recommended drying times. A general guide for drying 1 cup of herbs would be 1–2 minutes on high, moving the herbs every 30 seconds.

2. Air Drying

If you plan to air-dry herbs, cut the herbs before they go to seed. Tie the stems into bundles and hang indoors in an area with low humidity and good air circulation for best results. Avoid hanging herbs in areas with high moisture levels, such as near the dishwasher or sink. The time that it takes for air-drying to fully dehydrate herbs will vary greatly depending upon the herb, the weather and other factors. Herbs are dry when they crumble when touched (remember that Ohio weather is not always conducive to air drying).

3. Dehydrator Drying

Dehydrator drying is another fast and easy way to dry herbs. Wash herbs then dry the herbs in a dehydrator set at 95–115 degrees Fahrenheit for 1–4 hours. Drying times could vary depending upon the herb. A sure way to tell when herbs are dry is they will crumble and stems will break off.

How to Store Dried Herbs:

• crumble leaves (discard stems)
• store in airtight containers
• keep away from light, heat, and moisture

Best Herbs for Drying:

• rosemary
• thyme
• oregano
• sage
• lavender

Freezing Herbs

Freezing herbs is the method that preserves the most nutrients and flavors. Freezing slows the growth of microorganisms that cause food spoilage. While freezing does not eliminate these microorganisms, it does significantly slow their growth, allowing food that has been properly frozen to be safe to eat. It is important to note that once frozen foods have been thawed, microorganisms will continue to grow, so safe food-handling practices are needed. 

Tips for Freezing Herbs:

• Herbs should be frozen at their peak freshness for best results. 
• Although frozen herbs may be safe to eat after a year or longer, it is recommended that they be used within 3–6 months for best quality. 
• Keep your freezer at 0 degrees Fahrenheit. Keep a thermometer in the freezer to monitor temperature. 
• Herbs will have textural changes after being frozen and thawed. Therefore, herbs that have been frozen may be better suited for use in cooked dishes, rather than as a garnish or in uncooked dishes.

How to Freeze Herbs:

1. Wash and dry herbs thoroughly.
2. Chop (optional) depending on the use.
3. Choose a method:
   • Flat Freeze: Place whole leaves on a baking sheet (leave space between plants), freeze, then store in freezer bags.
   • Ice Cube Method: Chop herbs, place them in ice cube trays, cover them with water, broth, or oil, and freeze.
4. Label and date containers.

Best Uses of Frozen Herbs:

• soups, stews, sauces, cooked dishes
  (texture softens—less ideal for garnishing)

Best Herbs for Freezing:

• basil
• cilantro
• parsley
• dill
• chives
• mint

Preserving herbs by drying or freezing is a simple way to enjoy the fresh flavors, aromas, and nutritional benefits of your garden throughout the year. By harvesting herbs at the proper stage, following safe preservation methods, and storing them correctly, you can maintain their quality and reduce food waste. Whether you choose drying for sturdy herbs like rosemary and thyme or freezing for tender herbs like basil and parsley, taking a few extra minutes after harvest will ensure you have flavorful herbs ready to enhance soups, sauces, and many other dishes long after the growing season has ended.

Additional Resources

Note: This fact sheet uses language, recipes, procedures, and data from reliable sources such as the ones listed below. For the most part, the original text has been preserved because safety around food preservation is especially important. For safe and healthy preserved foods, be sure to carefully follow directions.

Download a PDF of this fact sheet

• Herbs
  (nchfp.uga.edu/how/dry/recipes/herbs)
• Herbs that heal
  (cfaes.osu.edu/fact-sheet/herbs-heal)
• Herbs that heal infographic
  (go.osu.edu/herbsthatheal))
• Selecting, storing, and using fresh herbs
  (ohioline.osu.edu/factsheet/hyg-5520)

• Food preservation: Freezing basics
  (ohioline.osu.edu/factsheet/hyg-5341)

Originally written June 24, 2016 by Joanna Rini Fifner, Extension Educator, Family and Consumer Sciences, Ohio State University Extension.