“The purpose of drying is to take out enough water from the material so that spoilage organisms are not able to grow and multiply during storage.” (Putting Food By)
Technically the USDA defines dehydrated food as having only 2.5 to 4 percent water left; this is unattainable with home drying. Dried foods are defined as having about 10 to 20 percent water left in them, which is very achievable with methods available at home. This does not apply to dehydrating/drying herbs as much, but I want to explain why I am talking about drying herbs versus dehydrating them.
As a note, when I refer to herbs in the rest of this post, I am talking about the leaves, whole flowers, or petals used for cooking or medicinals. Roots can also be dried, and I have a short bit of information on that by the information below on using the oven to dry herbs.
What does drying food require? Two things . . .
First, drying food requires heat strong enough to remove the water from the herbs, but not too strong that you end up cooking what you are trying to dry. It is the same principle as raising bread; don’t get impatient, set it to rise in too high of a temperature, and end up cooking the top layer of dough.
Drying herbs also requires enough dry, moving air to carry away moisture from the drying herbs. Attempting to dry herbs outside in very humid climates may not work very well even if it is hot.
Basic Steps to Drying Herbs
Regardless of how you dehydrate your herbs, the first few steps and the general principles are the same.
First you need to harvest your herbs by either trimming the whole sprig or just the top 5-6 inches of growth. Different herbs may benefit from different types of pruning, so be sure to learn about the specific herbs you are growing. The herb profiles here on the blog are a great way to do that!
Harvesting should be done at the herb’s peak, most likely in midsummer before they start to flower. (unless of course you are growing the herb for the flowers.) The ideal time of day to harvest is after the dew has dried, but before the heat of the day has caused the plant to lose any essential oils.
Pick over them to make sure you are not inadvertently bringing any bugs with you. Yesterday I found a butterfly chrysalis on my lavender plant that I was harvesting from; glad I didn’t dry that! Rinse your herbs in clean water, and pat dry.
Next, choose one of the methods below to dry your herbs. Each has their pros and cons, and you will probably end up finding a favorite. Personally I like using a dehydrator because it goes faster thus is easier because I have to think about it for a shorter period of time.
Different methods will take different amounts of time to dry your herbs. Thicker, larger leaves will also take more time than thinner, smaller ones. Keep an eye on your herbs as they dry to get an idea of how long your preferred method takes. You know your herbs are dry when they crumble easily and you can rub them together to crush them.
This applies more to food than to herbs, but the products you’re drying need to be protected from insects at all times. Nylon mosquito netting or a currently unused window screen can be laid on top of your drying herbs for this purpose. If you are drying them outside don’t forget to protect them from dew at night by either bringing the herbs inside, or covering them with a large box, etc.
Storing Dried Herbs
How do you store your dried herbs? Once you strip the leaves off the stems, they should be stored in an airtight container away from light. A pantry or cupboard is ideal for this, though a damp basement or root cellar is obviously not a wise place to store dry herbs because it is too wet. I wash and reuse glass jars that I can’t use for canning such as salsa jars or tomato sauce jars. If I have extra mason jars sitting around I use those, but save a lid by recycling one from a jar of canned goods that has already been used up. (Draw an X on the lid so you remember not to try to use it again for canning.) Also, remember to label your herbs with the name of the plant and when you harvested it. You may think you will be able to tell your herbs apart by appearance and smell, but I know from experience that you will not always remember what is what. Even if you are 90% certain that you are using the right herb, labeling them and being 100% confident provides valuable peace of mind!
Different Ways to Dry Herbs
So what are your options for drying your herbs?
Air Drying Herbs
The first, cheapest, and probably most straightforward way is to air dry your herbs. Herbs are particularly suited to air drying because they do not need to be dried at high temperatures.
A great way to air dry your herbs is to place a large brown paper bag like you would get from the grocery store over your bunch of herbs (10 to 15 long sprigs of herbs per bundles) and tie the opening of the bag around the stems. Hang up the whole contraption in a dry room with good airflow (not somewhere humid like the basement, laundry room, bathroom, etc.) When the leaves/flowers are dry, you can simply shake them off into the bag.
You can also air dry herbs by spreading them out on a screen, such as a window screen, and setting them up on something like chunks of firewood, cinderblocks, sawhorses etc. to allow air to circulate all around them.
Using an Electric Dehydrator
Your next option for drying your herbs is to use a dehydrator. Using an Electric dehydrator for drying herbs is not necessary because they dry so well at room temperature, but if you want to dry them more quickly, it will work very well. There are two types of electric dehydrators, a vertical flow dehydrator or a horizontal flow dehydrator. A vertical flow dehydrator houses the heating element at the bottom of the unit and blows the warm air up. This will work but is not ideal because the trays will not heat evenly, flavors will mix, and things can fall into the heating element. A horizontal airflow dehydrator houses the heating element at the back of the dehydrator, which allows the hot air to blow evenly over all the trays at once. Most dehydrators have an herbs setting, which is their lowest heat setting. I use my Excalibur Dehydrator to dry herbs almost overnight with excellent results. My only tip would be to make sure not to cram the dehydrator too full. Remove some trays and leave enough space between the herbs and the tray above them that they don’t touch.
Using an Oven
You can also use an oven, which can be used like a dehydrator with a bit of creativity. Using the bake setting on an electric oven (as opposed to broil) or just the bottom heating element on a gas oven, preheat the oven to 140 F/60 C, then turn it off to let it drop to around 100 F/38 C. Check the temperature with an oven thermometer. Herbs need a lower drying temperature than most foods do. Once the oven is warmed up, load it with your herbs. Putting Food By suggests using cake racks set on cookie sheets as an alternative to trays built for drying food, which I think is brilliant. This allows air to circulate and won’t accidently melt anything (Though your oven should not be that hot anyway- just a disclaimer!) Leave the oven door open a crack to improve air circulation or prop it open with a rolled up hot pad. Keep a close eye on your herbs as they dry- remember you want them to be crumbly, not charred!
A Note on Dehydrating Roots
The Reader’s Digest Back to Basics book has some notes on drying herb roots. This is not something I have tried yet, but it’s always good to be collecting knowledge! It says to dig the roots up in early spring or fall. After they are thoroughly washed, slice them thinly and set them out to air dry partially. They suggest finishing the drying process in a oven on low heat because air drying completely can apparently take up to two years! Roots are completely dry when you can snap them and they feel brittle.
Summing it Up . . .
So there you have it, the basics of drying, how to tell when your herbs are dry, different ways to dry them, and how to store them. Drying herbs is a great step towards further self sufficiency. The feeling of knowing what herb you need to treat a problem and reaching for a jar of herbs you grew and dried yourself to make the remedy is amazing! I want to strongly encourage you to start experimenting with saving your herbs for when your family needs them this winter. And remember, always keep learning!