Drying herbs is an easy way to keep them for use throughout the year. Herbalists follow some general rules when drying herbs, as well as specific guidelines for each part of a plant—flowers, stems/leaves, and seeds.
The main ingredients necessary for successful harvest/drying include warmth (but not excessive heat), adequate ventilation, and dry conditions.
Leaves
Herbal leaves can be harvested throughout their growing seasons, but most leafy plants reach their maximum potency during spring and early summer. When harvested for medicinal use, young, fresh leaves with low levels of components that degrade with heat or moisture are ideal.
Harvested leaves for herb medicines, including chamomile, arnica, calendula, and tulsi, should be harvested before their petals fully unfold to preserve their potency and use in tinctures, herbal vinegar, honey, glycerites, or herb-infused oils. Harvesting flowers or roots dormant in fall or winter makes harvesting simpler, as most energy has moved from above-ground growth into root development.
When harvesting herbs, try it on a dry day, as too much moisture can compromise their essential oils. Most herbs need at least one sunny day after rainfall to rehydrate and gain full potency before drying off.
As drying will require air circulation, harvesting sturdy stemmed herbs in small bunches should allow maximum potency levels. Tie them together using string to avoid them dislodging as they shrink during drying – rubber bands work tremendously, or twist ties can even work as effectively!
Herbs that are being dried should not be washed as this may promote fungal contamination during the drying process. Instead, they should be shaken or lightly brushed to loosen any debris clinging to them before being tied or placed in a well-ventilated space to dry for approximately one month.
The time it takes to dry herbs depends on several variables, such as climate and other environmental considerations, so it is wise to inspect and take action once they become fragile and easily broken apart.
Blossoms
Herbs that produce flowering plants for use in herbal medicine require constant harvesting throughout their growing season to avoid going to seed and losing their potency. Furthermore, they must be collected before fully opening, as this will divert their energy towards flower production instead of medicinal use and cause their potency to decline gradually over time.
When harvesting flowering herbs, the ideal time and date depending on their specific species and intended use. For general culinary herbs like chamomile, calendula, and feverfew with single clustered blooms like chamomile, calendula, and feverfew that present themselves in single clumps along the stem, it is best to harvest once their buds have opened but before fully opening entirely to retain maximum potency for use in tinctures, herbal vinegar, and oil infusions. Additionally, extra moisture could promote fungal contamination during drying processes, increasing the potency of these culinary gems for culinary uses like tinctures, herbal vinegar, or oil infusions.
Arnica, Cleavers, and Stinging Nettle should be harvested shortly after they begin opening but before reaching full bloom to retain their potency in tinctures, vinegar, oils, or glycerites and their aroma for longer.
Once herbs have been harvested, any excess moisture must be removed quickly before it causes dehydration. Rinsing in cool water or using a damp paper towel are both ways. However, for maximum effect, you should place them in a fantastic, dark location away from direct sunlight so they can dry without being disturbed by anyone or anything.
Once your herbs are dry, they should be sifted through to remove any debris and placed into jars or canisters for long-term storage. It is ideal to keep them somewhere cool and dark, where light or heat cannot speed up their degeneration process.
Seeds
Herbs that produce seeds, such as anise, caraway, coriander, and dill, should be harvested before they bloom and redirect their energy toward creating seeds instead of new leaves. Once mature seeds swell and turn brown or black, they can be collected; as with herbs that produce leaves, drying is the ideal method to preserve these seeds for use later in the year.
Herbal seeds can be dried using various methods, but it is wise to do it out of direct sunlight for best results, as UV rays degrade herbal oils and cause oxidation. While food dehydrators work best at this task, open baskets, clean window screens placed horizontally on wooden clothes drying racks, or tied bundles of seeds hung in an airy space are equally efficient methods of drying herbs with high volatile oil content.
An ice cube tray can also be an effective way for gardeners to store fresh herb sprigs or whole leaves for easy use in recipes while keeping their supply steady. Before freezing them, rinse and pat dry each sprig or leaf to ensure it doesn’t retain too much moisture when defrosted for use later.
Most herb leaves benefit from being dried in a dark, well-ventilated area with low humidity and temperatures that don’t get too hot to prevent discoloration. Swish them gently in cool water to loosen any soil particles before patting them dry with paper towels afterward.
Over-dried herbs often become dry and brittle with use and need to be rehydrated before being stored for use. To rehydrate them, place them in a plastic bag with just enough water to moisten their leaves without making them soggy. Allow these to sit in the bag for several hours while checking periodically so they stay moist and maintain quality. Once adequately rehydrated, they should be stored in an airtight container as recommended.
Roots
Herbs grown specifically for seeds should be harvested when they have completed flowering. Although this might seem counterintuitive, as many herb gardeners seek to increase production as much as possible from their plants, harvesting herbs for seeds is an invaluable way to increase genetic diversity within your population and support future growth. Seeds should be collected during dry, sunny weather with hand snips or using a chamomile rake to harvest the seed heads.
Be mindful that harvesting times vary for every herb; therefore, to learn when each should be harvested, it’s essential to monitor its behavior and read up on how dehydration should look and feel for that species. Oregano and thyme can be easily harvested by cutting a third of stems between summer and frost at regular intervals. This allows lower leaves to continue receiving sunlight for growth, ultimately contributing to its medicinal properties.
Other herbs, such as mints and lemon balm, should be harvested before they go to seed. When plants go to seed, their energy shifts toward blossom production rather than leaf production, and their medicinal potency declines significantly. Regularly deadheading flowers on these herbs can also help prevent them from going to seed by redirecting the energy they dedicate to leaf rather than seed production.
Roots are an exception to these harvesting rules when it comes to roots. Before drying herbs, they must first be washed thoroughly in cold water in a bowl – this method ensures most dirt settles to the bottom of the bowl so it can easily be rinsed away later.
After washing the roots thoroughly, they should be tied into small bundles using twine or string and placed in a warm and dry area to dry. Sufficient air circulation and low humidity levels must be provided to minimize the volatilization of aromatic compounds from volatilizing during this process.