Herbs are useful in cooking, home remedies and in gardening strategies like companion planting. They’re easy to grow, and can be preserved in a surprising number of ways. Once dried or otherwise stabilized for long-term storage, many herbs remain viable for up to two years. The scents and flavors that make herbs so useful to humans tend to discourage some insects and even critters like rabbits and deer. This makes herbs excellent options in an organic garden because they reduce the need for pesticides and other invasive pest control measures.
Reaping the Bounty
The best herb preservation strategies start at harvest time. The word ‘herb’ usually refers to plant leaves rather than flowers, seeds, bark, berries or roots, so we’ll restrict ourselves to leaf harvesting here. If you’re not sure how much of an herb to harvest for your needs, remember most herbs will shrink to about a third their normal volume but retain the same pungency as they would when fresh.
The following tips will improve your herb harvesting efforts:
- The tender leaves are often the part of an herb most susceptible to damage, so the first step in harvesting is to cause as little bruising as possible while preserving any parts of the plant that won’t be removed. If you expect to harvest a single specimen multiple times, wait for it to reach a height of eight inches or more, and only take a third of the foliage at any one time. Wait for the plant to regrow a like amount between harvesting sessions.
- Harvest plants before they flower. When plants begin diverting resources to propagation, they cut back on leaf production. For the most abundant, flavorful and aromatic leaves, harvest before the first buds appear. If you do detect a few buds, pinch them back. In many herbs, this will delay flower production and also discourage plants from bolting in hot weather.
- Harvest in the morning before plants are exposed to increased light and heat. Native oils are more likely to be concentrated in the leaves at this time. If your herbs are outdoors, wait for the dew to evaporate.
- Examine plants carefully, and choose only the healthiest specimens. This will reduce the chance of accidentally ruining a crop by introducing disease, insects, molds and other undesirable elements.
- Harvest whole stems with the leaves attached. This is a matter of personal preference, but harvesting whole stems will reduce bruising and make some drying methods, like air drying, easier to manage.
- If you plan to harvest more than a handful of herbs, transport them in a basket or other container with good airflow, like a mesh or wicker basket or even a paper bag. Avoid using plastic bags. They concentrate heat and retain moisture. Fresh herbs will wilt and even begin to steam if kept where heat and moisture accumulate.
- Maintain herbs in small, loose bunches. This improves airflow and reduces the risk of damage during harvesting and later.
"Removing moisture from plants concentrates their natural oils and creates a hostile environment for bacteria and fungi."
Preparing Herbs for Long-Term Storage
When preserving herbs, heat, light and moisture are the enemy. The same things that build strong, healthy fresh herbs can reduce pungency or even ruin those herbs later. That’s the reason herbal preparations are usually placed in cool, dark locations and stored in tinted glass vials with tight fitting seals.
Herb Drying Methods
Removing moisture from plants concentrates their natural oils and creates a hostile environment for bacteria and fungi. It also reduces volume while retaining nutrients and flavor. Drying isn’t the only way to preserve herbs successfully, but it’s an excellent place to start.
The oven seems like a logical place to dry herbs, but oven temperatures are often too hot, even on the ‘warm’ temperature setting available with most ovens. The goal is to evacuate as much moisture from herbs as possible without scorching them. Scorching will turn herbs slightly brown, often at the tips, and give them a bitter aftertaste. A temperature less than 200˚F is considered safe for drying herbs, but this is one of those instances where less is more. Around 150˚F is even better. At lower temperatures, drying will take longer, but plants will retain more flavor and better color. You can usually achieve a stable, low temperature more easily with a gas oven, but electric oven drying is possible with a little vigilant care.
Once dry, allow herbs to cool on your countertop away from direct sunlight. Remove leaves by grasping the stems and running your thumb and forefinger from the tip to the base using light pressure. The leaves should pop off easily. You can separate them right into a bag or other wide mouth container using this method. If you want crushed leaves, opt for a paper bag. Once full, you can depress the bag, shattering the leaves inside. You may want to preserve whole leaves for part of your harvest, though. Larger leaves will retain their flavor slightly longer than crushed leaves, and you can always crush whole leaves later as you need them. After processing, secure leaves in an air-tight container.
Drying Herbs in a Dehydrator
Dehydrators are designed to remove the moisture content from meats, fruits, vegetables, herbs and flowers. They contain multiple open trays, and heat is provided by a simple electric heating element. The trays rotate, usually manually, to bring them into greater or lesser proximity to the heat. Dehydrators are an effective way to dry food fast without as much risk of scorching as using a conventional oven. Because the trays are made of mesh, or include lots of small openings, moisture doesn’t linger. Inexpensive models are completely manual and lack monitoring controls. More sophisticated dehydrators have fans to distribute heat evenly and may include temperature controls. Most dehydrators are designed for low-volume projects.
Drying Herbs in the Microwave
If you’re really in a rush, you can use the microwave. It’s a convenient option, but has a down side. Aggressive drying measures like this can have a negative impact on the color and flavor of delicate herbs, so be warned. To use the microwave for drying, place herbs in a single layer on a paper towel. Maintain at least a quarter inch between stems. Cover the batch with a second paper towel. Microwave for one minute, and then open the microwave door to vent excess steam. Repeat until herbs are dry to the touch. This should take two to three minutes. Let herbs cool and check for doneness. The leaves should break into pieces when pinched. The idea here is to heat the herbs in short bursts, and then allow any steam to vent well before applying the next blast of microwaves. Venting keeps herbs from steaming before they dry.
Indoor Hanging and Drying
Air drying herbs in an attic or dangling from a shadowy ceiling is a time-honored way to prepare and store herbs (and it can look pretty beguiling). If you want to try it, it may take days to dry herbs completely, but it’s a fun and traditional option. Gather herb stems together in loose bunches to reduce the chance of mold damage. Prefer rubber bands to twine for this one. The bands will snug up as the stems lose volume, keeping the bunches together. Check for doneness with the pinch test after a week to 10 days. The warmer and dryer the weather, the faster the herbs will cure.
Outdoor Air Drying
You can air dry herbs in a few hours outdoors on a warm day, too. Place loose bunches in paper bags from which you’ve removed the bottoms, effectively creating paper wind tunnels. Gauge the wind direction, and position each bag so air flows freely in one end, and out the other. Herbs should dry within a few hours. You can also dry herbs outdoors in the shade using mesh flats or old window screens, much as you would in a dehydrator. Again, choose a clear, warm day, and avoid crowding herbs, which can cause uneven drying. Can you hang herbs outdoors in the shade to dry? Sure, but the area around the band or string will dry slowest, and may be vulnerable to any mold spores floating by.
Be creative. That’s one of the things that make herbs so remarkable. With a little work, you can become a maestro in the kitchen, restock your first aid kit and beautify your home, all through the strategic use of your gardening expertise.