Drying Herbs: A Complete Guide

 

This guide will discuss in detail everything you need to know about drying herbs. I explain the differences between drying herbs in the sun vs the shade. And drying herbs indoors vs drying herbs outdoors. We’ll talk about drying herbs in bunches, on racks, in ovens, and more.

I also want to speak about the differences between dry herbs and fresh herbs. And of course, the most important part, when to harvest herbs for drying. Some of these herb drying techniques are as old as the hills. While other techniques, like drying your herbs in an air fryer, are more recent. Do they work as well? 

We will find out! 

Let’s get started!

Why Do We Dry Herbs?

We dry herbs for the following reasons:

  • To remove moisture – while drying will see the destruction of certain volatile phytochemicals, there are also many advantages. In some cases, phytonutrients become concentrated after drying.
  • To store them – it is not always possible to use up freshly picked herbs so we dry them to store, in order to have a year-round supply.
  • To increase shelf life – Drying herbs preserves them.
  • To reduce the risk of fungal infections and molds (microbial contamination).
  • To dry them out in order to increase the efficacy – depending on the type of herb.
  • To get herbal teas for medicinal use
  • To have an on-hand supply for culinary use

As you probably know, from growing your own herbs, not all herbs live forever.  Annuals have one growing, budding, flowering, and seeding cycle. And then the plant dies. Biennials, last for two seasons and a good cutting back, at the right time, will give us an abundant second “crop”. Perennial herbs can grow for 4-5 years, even longer. 

So how and when you harvest for drying will depend on what type of herb it is, annual, biennial, or perennial. 

We dry herbs to store them. Often, especially if we are growing and drying herbs for home use, we won’t manage to use all the fresh herb available. So by picking them and drying we ensure our supply of fresh, organic herbs will be available all year round.

What Happens When We Dry Herbs?

When we dry herbs the moisture evaporates. When this happens volatile phytochemicals also evaporate. But others actually become more concentrated. This means that drying herbs, and using dried herbs, will sometimes be better than using the fresh herb.

The essential oils of herbs are concentrated in the leaves. So a lot of the aroma and oil will be lost through drying. But sometimes drying herbs actually results in phytochemicals being present that were not present in the fresh material!

Great care must be taken from the time the herb is harvested right up until it gets stored. Handling the plants will bruise the leaves and further reduce the amount of oils found in the trichomes of the plant. (The trichome is an appendage like a hair or glandular sac, found in leaves, stems, and bark)

Drying Herbs in the Shade vs Drying Herbs in the Sun

If the conditions allow for it, you can dry herbs outside. But make sure you set up the drying area in a clean, dust-free area, that will not get direct sunlight or wind. If the herbs are exposed to direct sun, the volatile compounds (essential oils) will evaporate and you will be left with a poor quality herb.

The area where you dry herbs outside must also be sheltered from the rain. If the herbs get wet during the drying process, the yield will be lost. fungus and molds set in almost immediately.

Drying herbs in the shade allows the herbs to dry out quickly while still retaining the color and aroma that is so important for getting good quality dried herbs to use for cooking as well as herbal teas. 

Can All Herbs Be Dried?

The less moisture in the herb the better it will dry. It will also influence the method you use. The method you choose will be based on the answers to the following questions:

  • What herbs are you drying? Low moisture or high moisture?
  • Which part of the herb will be used? The seeds, leaves, flowers, or roots?
  • What will you be using the herbs for? Medicinal or culinary?

Herbs will be low-moisture or high moisture. Low moisture herbs can be air-dried. High moisture herbs need to be dried as fast as possible. Because of the moisture content, they will be more susceptible to fungus and other microbial organisms, all of which compromise the quality of the dried herb product. Using a dehydrator works well for high moisture herbs.

List of Low Moisture Herbs

low moisture drying herbs

Low moisture herbs  – ready to be hung and air-dried

  • Rosemary
  • Thyme
  • Lavender
  • Bay 
  • Sage
  • Bush Basil (perennial basil)
  • Marjoram
  • Oregano
  • Bergamot
  • Hyssop
  • Lovage (perennial celery)
  • Savory (summer and winter)
  • Borage
  • Comfrey
  • Khakibos (an herb that repels fleas on pets)
  • Angelica
  • Horseradish
  • Lemon Balm
  • Lemon Verbena
  • Rue
  • Salad Burnet
  • Tansy
  • Tarragon
  • Wormwood
  • Sorrel
  • Feverfew
  • Elderberry

List of High Moisture Herbs

  • Parsley (all varieties)
  • Mint (all types)
  • Coriander (cilantro or dhania)
  • Sweet Basil (annual basil)
  • Fennel
  • Dill
  • Watercress
  • Chervil
  • Geranium
  • Chives
  • Caraway
  • Purslane

List of Herbs Dried for Seeds

  • Anise
  • Celery
  • Dill
  • Coriander
  • Fennel
  • Fenugreek
  • Mustard
  • Cumin
  • Chia
  • Alfalfa

List of Herbs Dried for Flowers

  • Rose
  • Calendula
  • Viola
  • Chamomile

List of Herbs Dried for Roots

  • Dandelion
  • Chicory
  • Valerian

List of Herbs Dried for Leaves

  • See the lists of low and high moisture herbs

Herb Drying Methods

There are many ways to dry herbs. Some work better than others. It makes sense to use the best technique to dry herbs, that will store well, and still contain the beneficial phytochemicals needed for herbal remedies to work properly. It is also important how you pretreat herbs before drying.  

Blanching – a pretreatment

Blanching is a method  that sees fresh herbs being immersed in hot water for an allotted time, usually just a few seconds (between 4-20 seconds depending on the herb). Dill is sometimes blanched in water for a whole minute. Sometimes a weak solution of water and citric acid is used. Herbs can be steam-blanched, water-blanched, or blanched by microwave. Each technique delivers different end results. Once the herbs are removed from the water/steam they are ready to be dried. 

There are two main reasons for blanching herbs before drying:

  1. Blanching helps to retain the color of the herb
  2. Blanching reduces the drying time.

For example, steam-blanching parsley leaves for 15 seconds not only retained good chlorophyll (green color) but also improved lutein content and speeded up the drying process by 30%. Similar results were seen with dill that was water-blanched for a full minute.

Once blanched, several drying methods can be used. Vacuum-drying and through-flow drying is is done at 45°C, while cross-flow drying is done at 40°C. Freeze-drying is also used with success. These temperatures are ideal for acheiving the best phenolic, flavonoid and tannin levels in the dried herbs.

List of Herb Drying Techniques

When it comes to commercial herb drying the techniques used get very technical. And often there is a pre-drying method that gets applied,like blanching. For the purpose of this article, we will focus on drying herbs at home. 

Commercial herb drying methods are constantly being tested to improve the time it takes to dry herbs as well as the quality of the end product.

Methods for drying herbs on a commercial scale include:

  • Solar-powered drying systems
  • Fluidized bed solar systems
  • Using electrical impulse fields (pre-treatment)
  • Using ultrasound (pre-treatment)
  • Solar-hot air dryers
  • Microwave-vacuumed dryers
  • Heat pump integrated systems
  • Supercritical carbon dioxide drying

Herb drying techniques for home drying include:

  • Air drying – the most common and easiest method of drying herbs
  • Freezing – although not strictly a “drying” method, freezing is one way of storing herbs that don’t dry well.
  • Dehydrating – you can use an oven but it is slow and if heat is not low enough sometimes the herbs will lose efficacy. Using a proper dehydrator works best.
  • Air-fryer – Air-fryers have a setting that dehydrates so using an air-dryer to dry herbs at home is an excellent method.

How To Dry Herbs from Home

First off, let’s get the methods that don’t work out of the way. People often ask these questions about drying herbs.

Q. Can you dry herbs in a microwave? 

A. Yes, but don’t do it! Microwave drying will more than likely nuke your herbs, obliterating any goodness.

Q. Is drying herbs in an oven okay?

A. Yes, but too much heat will destroy important bioactive compounds. So if you use an oven make sure the door remains open and the heat low. 

Q. Can you use a dehydrator to dry herbs?

A. Absolutely, and this is a method that works well.

Q. What is the best way of drying herbs at home?

A. The best way of drying herbs at home is the way that herbs have been dried since the beginning of time! Good old-fashioned air drying. And this is the technique we are going to explain here today.

How to Air Dry Herbs

 

Carolyn Thomas of Homesteading Family shows us how to air dry culinary herbs, from home.

The most important things to remember when drying herbs (indoors or outside) are:

  1. The area must be well-ventilated.
  2. The herbs must not get direct sunlight.
  3. Make sure the area is clean and dry to reduce the risk of dust and microbial interference.
  4. If drying herbs outside, they must be placed in a shaded area. While it may be good to sun-dry fruit, it is not good to dry herbs in direct sunlight. The essential oils will be destroyed.
  5. You will need a drying rack. You can purchase drying racks but it is easy to make your own by using materials you may have around the house. Be inventive, you can use a clotheshorse or any type of stand that you can attach bunches of herbs to.
  6. You can also set up a temporary washing line in an empty room or area of the house that is well-ventilated and does not get full sun.
  7. After cutting the herbs, divide them into bunches. Tie each bunch together with the stems facing up and the leaves and flowers facing down. Hang them or attach them to your rack or line by turning the bunches upside down. Once they are hanging upside down you can leave them to dry.
  8. They will be ready when you can take a few leaves in your hand and crush them easily.
  9. To store them it is best to crumble the dried leaves lightly and place them into an airtight jar. If the jar has clear glass make sure they are stored in a cool, dark cupboard. 
  10. Always label the jars with the date and name of the herb.

food in brown container

Green Matcha Tea – dried and ready to use (photo by Antonio Wemer – unsplash)

How to Harvest Herbs for Drying

There is no set season to harvest your herbs. It will depend on what type of herb, where it’s growing, and the climate, or zone, you are in.

  1. Harvest in the morning. Make sure it will be a hot, dry day. And wait until the dewdrops have dried.
  2. When picking for leaves: Harvest herbs before the flowers open.
  3. Cut the stems 6″(15cm)  below the tips. And preferably make the cut just above a node. This will encourage new growth and make it possible to get another harvest out in one season.
  4. Collecting seed: Wait until flowers are finished blooming and the seeds are dry on the plant. Cut the entire stalk. Gently place into a lined basket and keep the different herbs separate.
  5. Harvesting roots: Once the leaves start to die back you can dig up the plant. Wash all soil off. This is one time where sun drying is encouraged. Make sure it’s completely dry before storing.

Benefits of D ry Herbs vs Fresh Herbs

A review by Grant Thamkaew and two of his associates describe how important it is to maintain the integrity of the essential oils of the herbs. How you harvest, handle, and prepare herbs for drying will affect the aroma and the color of the end product.

Commercially dried herbs are mostly inferior to fresh herbs in the culinary sense. This is because culinary herbs are used for flavor. A lot of the flavor is derived from the aroma so when herbs are dried carelessly or handled too much during the drying and packaging processes, the quality is affected.

As mentioned above, modern high-tech techniques are used to dry herbs on a large scale that guarantees a dried herb with better flavor. But air-drying small batches at home are great if you have excess herbs and want to store them for use over the course of 3-6 months. After that, they will no longer hold aroma and so will impart less flavor. Fresh is always best for cooking. 

On the positive side, herbs that get dried for their medicinal benefits need to retain the phytocompounds unique to each herb. And when herbs are dried (as opposed to fresh) the antioxidants and other beneficial phytonutrients become enhanced in their efficacy. So it is important to know before drying what you will be using the herbs for. 

The essential oils are present in the trichomes (leaves, stems, flowers, bark). 

How to Use Dry Herbs Medicinally

Herbs to be used medicinally are defined by the content of bioactive compounds. These compounds are found in the essential oils. The essential oils must, therefore, be “locked-in” during the drying process. Preserving the trichome integrity will improve the yield of essential oils.as well as the aroma quality. “Preserving the trichomes” is just a fancy way of saying that the parts of the dried  plants that store the oils must be treated delicately. 

Herbs can be dried and stored for use as herbal teas. Herbal teas are used to treat a wide range of minor and major ailments. When herbs get dried for teas, they will lose a large amount of the volatile compounds.

When herbs are prepared specifically for use as essential oils they will be distilled using steam, among other methods. This process ensures the volatile compounds can be extracted for use.

When herbs are dried for teas about 90% of the volatile compounds may be destroyed but it is the other 5-10% of the non-volatile compounds that hold much of the beneficial compounds, such as sterols, saponins, and other non-nutrients like antioxidants. And this is what we take from dried herbs that get used for teas.

How to Use Dry Herbs in the Kitchen

Dried herbs can be used in a number of ways in the kitchen but tend to lose their aroma quite fast. When using dried herbs, add them quite early during the cooking process. This allows them to become infused with the oil or liquid that is being used to cook with.

But with fresh herbs it is usually best to add them just before serving or during the last phase of the cooking process. This allows the heat from the dish to release the aroma from the fresh herb.

Resources

For those of you who shop online here is a shortlist of links you can follow if you want to purchase any of the following:

Herb Seeds: 

For those of you that don’t already have herb gardens or potted herbs – It’s NEVER too late to start your herb garden. Get fresh herbs from your nearest garden center or nursery or grow some from seed.

Choose from 10-15 varieties. All heirloom, organic and non-GMO – Heirloom Herb Seed

Dehydrators:

Top of the range dehydrator – suitable for homesteaders and people drying herbs in bulk.

Economy dehydrator – suitable for drying small batches at a time.

Drying Racks:

Wire Mesh Hanging Basket – 8 layers

Standing Rack with mesh – 8 layers

references

https://www.tandfonline.com/doi/full/10.1080/10408398.2020.1765309 (review of herbs drying in shade vs sun)

Gilbert, Zoe, Herbs for the South African Garden and Home, Struik Publishers, 1987

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