Do you find yourself with more herbs than you can use? Fresh herbs are one of the greatest benefits to home gardening, but how can you preserve these beautiful plants for use in the off-season? After all, herbs thrive best when pruned regularly.
Every cooking enthusiast knows that few things make more of a difference in the kitchen than adding fresh herbs to your recipes. It’s not only flavor, but also aroma and that bright pop of color that makes dishes look even more delicious.
But especially during the winter months, fresh herbs are hard to come by, so preserving them can be really helpful. Any type of herb can be saved—from woody ones like rosemary and thyme, to leafy varieties like basil and parsley.
So whether you have a lush backyard garden, keep some oregano and mint growing on your windowsill, or just don’t want that delicious cilantro you purchased to go to waste, there are some great and easy ways to make your fresh herbs last for months to come.
Depending on how many you have to preserve and how creative you want to get, there are great options suitable even for novices.
Although preserving herbs is fairly simple, there are a few important things to keep in mind. Sharon McDonald, food safety specialist at Pennsylvania State University, says improperly preserved herbs “could be a potential source of botulism.” But that’s not all. Karen Fifield, a food safety specialist at Michigan State University’s Montmorency County extension office, also warns that though they are uncommon, food-borne illnesses could lead to serious long-term repercussions, ranging from arthritis.
But don’t be scared off. A few simple precautions are all you need before you can get creative. Here’s how to safely prepare your herbs, and then a few ideas for what to do with them.
Before you start
As with any food preservation technique, starting with a clean, fresh product is key. Regardless of what kind of herb you are preserving, begin by thoroughly washing and drying them—this goes whether you grew them yourself or bought them at the grocery store.
To be certain you kill off all bacteria, McDonald recommends going an extra step by dipping your herbs in a sanitizing bleach solution with a ratio of one teaspoon of plain chlorine bleach to six cups of water. After that, rinse them well, and let them dry thoroughly.
Now that your herbs are squeaky clean, you have three options to save them.
1. Dry them
Drying herbs is a simple and surefire way to preserve them for many months to come. For the best results, Fifield suggests hanging small bunches of herbs (tied by the stems with twine or a rubber band) until they are dry and crunched up. Make sure to choose a cool, dark area—bright light will fade the color and flavor of the herbs. To prevent any dust or other contaminants from gathering between the leaves, hang them in a paper bag punched with a few holes to let air circulate.
Alternately, you can speed up the process by using a dehydrator or laying your herbs out flat on a baking sheet in an oven at 200 degrees Fahrenheit for one to two hours, or until they can be easily crumbled.
You can also put a few sprigs between two paper towels and microwave them for two to three minutes to start, and then in 30 second spurts until they’re dried out. This technique preserves color and flavor really well, but you run the risk of burning your herbs to a crisp. Make sure you do small batches, and keep a close eye on your microwave during the whole process.
Once fully dried, put the herbs in an air-tight, sterilized jar, and store them in a cool, dark place. You can use them just as you would store-bought dried herbs.
Bonus: make your own herb salt
For a creative and tasty variation on drying, you can make your own herb salt using any combination of woody herbs, such as rosemary, thyme, sage, marjoram, savory, or even lavender. Herb salt packs big flavor, which means you will use less of it in the long run.
Use a ratio of about 1/2 cup of kosher salt to two cups of fresh herbs, picked from the stems—a mix of herbs is nice here, but even just one variety will work. Combine the herbs and salt in a food processor, and add a few cloves of garlic if you like. Pulse a few times until the whole mixture resembles coarse salt.
Spread it out on a sheet pan and allow to dry out for a day or two, stirring it up on occasion. Transfer the finished salt to sterilized air-tight jars and store in a cool, dark place. Herb salt is excellent on everything from eggs to meat.
2. Freeze them
To preserve the fresh taste of herbs, freezing is an easy, safe, and tasty method. Bacteria need a temperature between 40 and 140 degrees Fahrenheit to grow, so the best way to keep food safe and bacteria-free is by freezing or refrigerating it. “That doesn’t destroy any bacteria that’s present,” McDonald explains. “But at least they’re in a dormant state.”
After the herbs have been cleaned, you can chop them up and put them in ice cube trays, fill the trays with water or olive oil, and freeze them. (It might sound obvious, but Fifield likes to remind folks to use drinkable water for this). To add instant fresh flavor, add these herb cubes directly to sauces, soups, and more. If you’re using water, do not add them to anything containing hot oil since it might splatter.
Here, you can get creative. Create a pesto using just about any combination of herbs and nuts blended with oil, Parmesan cheese, and garlic, and freeze it in air-tight containers. Leave in the refrigerator overnight to thaw, and use it as pasta sauce or sandwich spread.
Bonus: make herb butter
A compound herb butter is another delicious way to put those herbs to good use, and a fun way to play with flavor combinations. Leafy and woody herbs work equally well, and can be supplemented with garlic and citrus zest.
To make, finely chop up herbs (and garlic, if using) and mix well with soft butter—salted or unsalted both work here. Put it in the middle of a sheet of parchment paper and roll the paper around it to form a tight log. Wrap plastic wrap and aluminum foil tightly around the parchment to prevent freezer burn, and store it in the freezer for up to six months.
Whenever you want to add the butter to your dishes or directly onto toast, simply use a sharp knife to cut off a few slices.
3. Use them to infuse oil
Though this is one of the most popular ways to preserve fresh herbs, it’s also the most risky, so we warn you to proceed with caution.
Infusing oil can be as simple as putting a few sprigs of herbs into a small bottle of oil, but conservation can be a challenge. Store-bought infused oils undergo commercial processes that preserve them and inhibit the growth of bacteria—that’s what makes them have a long shelf life. But when you’re infusing oil at home, the stakes are higher.
“Herbs could contain Clostridium botulinum, a bacteria that’s widespread in the soil,” McDonald says. “If herbs are put in oil, you’re creating an oxygen-free environment that could favor the growth of Clostridium botulinum spores.” In other words: homemade infused oil can get moldy pretty fast.
If you decide to go this route, experts recommend storing your oil in a sealed container in the refrigerator, and using it within three to five days.
However, according to the University of Idaho, if you’re infusing your oil with garlic, or a combination of basil, oregano, and rosemary, the safest way to do it is by using citric acid. Before infusing the oil, soak the herbs or garlic at room temperature in a 3% citric acid and water solution for 24 hours. This will acidify them and limit the growth of the botulism bacteria.
After 24 hours, take your herbs or garlic out of the citric acid solution and put them in a bottle of oil of your choosing for one to 10 days—the longer you let it sit, the stronger the flavor. Oil infused with acidified ingredients will be safe to use for longer even at room temperature. You can find more specific measurements and instructions here.
You can also add some herbaceous flavor to your beverages by adding a few sprigs of clean, fresh herbs to alcoholic drinks such as vodka or rum, or simple syrup. The latter should be refrigerated and used within five days, while high-proof alcohol should kill pesky bacteria and can be stored at room temperature, or, to be safe, in the fridge.
Next time you realize you have more herbs than you can use on your hands, know there’s an array of options for saving them for a rainy day. Plus, you’ll be decreasing food waste while increasing flavor, so it’s a win-win.
Written by Katherine Martinelli for Popular Science and legally licensed through the Matcha publisher network. Please direct all licensing questions to firstname.lastname@example.org.