Drying Herbs

Why drying wild plants? 

• Preservation: Drying is an effective method to preserve wild plants. By removing the moisture content, drying helps prevent spoilage. Dried plants can be stored for extended periods, allowing you to enjoy their flavors, aromas, and medicinal qualities throughout the year, even when the fresh plants are not in season.
• Base for many herbal preparations: Many wild plants possess medicinal properties and have been used for centuries in traditional herbal medicine. Drying these plants helps preserve their medicinal compounds, making them suitable for preparing herbal remedies, teas, tinctures, herbal oils or topical applications.

How to dry plants?

This step is among the most important, as a good quality drying will retain most of the aroma over a period of about 1 year. On the other hand, poor drying, too hot, too exposed to the sun, too long or in a too humid leads to a lost in herb properties, smells and tastes.

The purpose of drying is to remove water from fresh plants to prevent the development of microorganisms, oxidation and rots, while retaining their quality and roperties. To be able to stabilize herbs quickly and without damaging their constituents and thus preserve the aromatic and medicinal properties, herbs must be dry under certain conditions:

• Away from light and direct sunlight
• In a dry and well ventilated place
• With a drying temperature around 25-30 °C

UV radiation is harmful to a wide variety of biological systems, and can even damage the DNA of cells. For aromatic and medicinal herbs the main risk is the destruction of their constituents. A dry, well-ventilated area will allow the plants to dry faster and therefore reduce the risk of the plants oxidizing. More than the temperature, it is a well-ventilated place that make the plants to dry.

Plants produce a large number of chemical compounds which can begin to evaporate when exposed to temperatures above 25°C. Other compounds, of higher molecular size, will resist up to temperatures of 35 °C. However, when drying, we want keep these compounds in herbs, that's why it is important to dry the plants with a mild temperature between 20 to 35 °C. In addition, just like UV, high temperatures destroy constituents. I can guarantee that drying above 50 °C changes herb colors and lose some of their aromatic and volatile compounds. The best is to not exceed 35 °C.

Preparing plants

Once picked, spread plants out on a table for a few hours away from light in order to let insects go. Avoid cleaning them with water, especially flowers. Sometime you might harvest roots to dry, such as dandelion roots. Execeptionally, wash them with water, rubbing well to remove the soil. Cut them in half across to check that there are no larvae or worms inside. Then cut them into sections and proceed to drying. Below we go through different drying methods.

Drying machine

Choose a dehydrator with the hot blast pushed horizontally and make sure that it is a dehydrator for which you can adjust the temperature below 30 °C. If you choose an upward wind dehydrator, place the most heat-resistant herbs at the bottom (where the wind blows) and the more sensitive plants upwards.

This method allow a fast drying of plants using less enery than oven drying. By drying plants with constant temperature within 24 h, it keeps their characteristic odors and colors.

All plants can be dried in a dehydrator. It is the best way for drying sensitive flowers, such as elder flowers, because it helps preserving their aroma and color while speeding up the dehydration process. It is also very good for flowers from the Asteracea family, such as dandelion flowers (Taraxacum sp.) because these flowers must be dried quickly otherwise they begin to go into seeds.

Hanging bouquets

This technique does not work for too sensitive plants. For instance, I tried to dry elder flowers in this way but it took takes too long and flowers oxidized becoming brown. However, it is a very good technique for large harvest of resistant plants such as yarrow (A. millefolium), raspberry stems with leaves (Rubus idaeus), or mugwort (Artemisia vulgaris).

Do not make to thick bouquets so air can grow through and dry the plants.

Drying on racks

Drying on racks is a method widely used by professionals. They built large drying rack that they place in a well-ventilated, warm and dark room.

Both methods consit of arranging the plants in a single layer on drying racks or table ensuring they are not overlapping. Make sure there is enough space between plants for air circulation. Having a single layers helps to prevent mold or mildew formation during the drying process. Allow them to dry naturally. Depending on the type of plants and temperature or humidity of the room, it may take from a few days to a week to fully dry. Monitor regularly and turn them over if necessary.

Testing for dryness

Before storaing them, check if the herbs are dry, by simply touching the leaves. They should feel dry and crumbly. Plants should be easy to crush a small portion between your fingers. If the herbs crumble easily, they are sufficiently dried.

Storage and conservation

Once dried, place plants in airtight glass jars. Avoid powdering them which risk to release aromatic compounds. Label with the herb name, the month and year of harvest. Dry plants do not keep indefinitely. The quality of the drying, the humidity and the temperature of the pantry in which they are kept will affect the storage time. As well as the number of times the jars are going to be opened during the year. This is why it is advisable to keep dried plants for up to a year, since then they will lose their properties, often by oxidation over years.

I find it a pleasure to renew the pantry every year. Nature gives us fresh plants every year, so why not take advantage of it and renew the pantry yearly instead harvest too much and leave plants for years before being used ?

Drying herbs is my favourite way to preserve wild plants.

• Culinary uses

wild chives, elder flowers, nettles, can be used for seasoning, spreading like any other culinary herbs on food. I used to make herbal salts, simply by blending dried plants with salt. Herbal oils or vinegars are also very good options, for seasing salads. I can recommand “Det Nordiska Skafferiet” of Johan Björkman, a very good Swedish book on using herbs in fermentaions, vinegars, oils and salts.

• Herbal teas

This is the way I use most of the plants I forage. I create herb blends by combining different dried herbs to suit your taste preferences or needs.

• Homemade skincare

I every year forage and dry plants for herbal skin care, such as yarow, elder flowers, plantain, dandelion flowers, comfrey, St John wort, etc. I used to make herbal infused-oils to later make herbal salves and creams as we will see in the session 5 of the course.

Before storaing them, check if the herbs are dry, by simply touching the leaves. They should feel dry and crumbly. Plants should be easy to crush a small portion between your fingers. If the herbs crumble easily, they are sufficiently dried.