What is an Herb-infused Oil?
Oils that have been laced with herbs, allowed to stand, and strained out of those herbs take on the scent and other properties of the herbs. That is the essence of an infused oil. Professional herbalists use herb-infused oils as a basis for many topical preparations, including massage oils, salves, and balms. Home herbalists can easily extend their use into the kitchen and bathroom or spa, which makes herb-infused oils a handy herbal remedy to keep around.
What Kinds of Herb-infused Oils are there? What Oils Should I use?
There are loads of really good books and courses on making herb-infused oils and other beauty preparations using oils, and it is really easy to get overwhelmed by the array of potential combinations available between the various types of oils you can use and the many, many potential plants you can try. Oils have a variety of properties in common, like being generally moisturizing and nourishing to the skin and nervous system. Just like the plants they come from, they have a wide set of variations, too. Some are more moisturizing while others tend to absorb more readily. Some contain fatty acids that are particularly good at rejuvenating skin while others have properties connected to reducing inflammation. As you work with herbal-infused oils more and more, exploring the variety available can be a lot of fun.
For the Home Medicine-Maker, especially one who is just starting out, it makes a lot of sense to narrow the field considerably by focusing on what is easily available. For the most part, you can use any pure cooking oil or fat as the basis for an herb-infused oil. This includes animal-based oils, like lard and butter. Herbalists in the Southern Tradition have likely encountered, used, and made herbal-oil preparations using lard at least. Most of us, however, tend to focus more heavily on plant-based oils in our home and professional practices. Vegetable oils tend to be rather shelf-stable and inoffensive to a wider variety of people, both at home and in the clinic. And, they’re generally easy to find at the local grocery store for a reasonable price.
The two oils I tend to reach for most often are Olive and Grapeseed. Both are readily available in my local groceries and are fairly low-cost. Olive Oil generally has a more oily feel when applied topically while Grapeseed oil tends to soak in deeply and quickly. Olive oil has a stronger flavor and scent, that of olives, while Grapessed oil tends to have very little scent and flavor. They’re both good, practical oils to keep on-hand that can be used topically or internally, making the herb-infused oils I make with them highly adaptable to my family’s needs.
Other oils you might consider include Sesame oil, which is highly valued in Ayurvedic practice; Sweet Almond oil, which is often used in massage oil blends for its lubricating properties and ability to soak in fairly quickly; and Avocado oil, which has a lot of nourishing properties for the skin. Oils to avoid include Canola, Vegetable, and vegetable shortenings, mainly because most of these oils have been highly processed, which degrades the quality and health benefits of them. If, though, that’s all that’s avilable, then go for it. So long as they’re food-grade, they may serve you just fine.
Which Plants Can I Infuse into Oil?
Knowing how you intend to use your herb-infused oil will help you decide which plants to use. The reality is, you can infused just about any dried plant into oil and you’ll likely get at least some of the plant’s properties to transfer into it. If you’d like to narrow that field a bit, consider looking for plants that are either highly resinous, like Larrea or Yerbe Santa, or plants that are rich in essential oils, like Rosemary or Lavender. Resins and volatile oils tend to transfer into oils quickly and easily. We have a variety of plants, like Saint John’s Wort and Cottonwood, that have long been prized for the medicinal qualities of the herbal oils they make, too.
Other plants that have long been part of the herbalist’s herbal oil pantry include:
- St. John’s Wort
- Yerbe Santa
- Rose (petals)
- Cottonwood (buds)
The key to success, especially as you’re starting out, is to use dried plants whenever possible. With few exceptions, it is wise to avoid introducing any water into your oil for any reason. The presence of water in your oil can cause fermentation and rancidity. Working with fresh plants requires extra care and a whole lot more monitoring than does working with dried plants. At the very least, you need to let the fresh plants wilt a while before adding them to the oil and then monitor them closely as they infuse. Herb-infused oils made from fresh plant material are also less shelf-stable than their dried-herb counterparts.
How do I Infuse Herbs into Oil?
There are two basic methods for infusing oil with herbal properties: The Hot Method and The Cold Method. The difference is as simple as it sounds. The Hot Method requires heat and tends to work a lot faster although it opens you to the risk of oxidization in your oil. The Cold Method takes longer but is far more simple and tends to better protect your oil from oxidizing.
You’ll use a ratio of approximately 1:4, one part herbs by weight or volume to four parts oil by volume. If you’re making herbal-oil for a clinical setting, you’ll weigh your herbs rather than use volume to measure them. If you’re making a folk-method herbal oil, you can use a rough estimate of the volume. The more you make herbal oils, the better a feel you’ll get for what makes an oil of the strength you desire.
How to Use Heat to Make Herb-Infused Oil
You will need a heat source, like a small slow-cooker or a stove or oven. The important part is to monitor the oil’s temperature and keep it low enough to warm the oil but not so hot it cooks or fries the herbs. If you’re using the stove, you will need a pot large enough to hold all the plants and oil and leave room for stirring. If you’re using the oven, you’ll need a pyrex glass or casserole dish large enough to hold all the plants and oil and leave room for a little sitrring. If you’re using a slow-cooker, be sure it will stay at a low enough temperature to culture yogurt but not boil water (or fry your herbs in the oil).
- Measure the herbs into your pot, slow cooker, or casserole dish.
- Add the oil to the pot, slow cooker, or casserole dish.
- Turn on the heat. For a slow cooker, use the warm or low setting. For a stove, use the low setting. For the oven, use the lowest setting your oven offers. In all cases, aim for around 120-140 degrees F (49-60 degrees C).
- Let the oil mixture heat for at least a few hours. If you’re using a reliable slow cooker, you can let it stand overnight. For the stove or oven, keep an eye on it to ensure the heat doesn’t start to creep up. Stir the mixture occasionally and inspect the herbs to ensure they’re not starting to fry or get crisp. If they are, lower the heat or take it off the heat entirely.
- When the oil has heated awhile, take it off the heat and let it cool.
- When it’s cool, strain the herbs from the oil. Discard or compost the herbs as makes sense and bottle your oil. Be sure to label it, too.
How to Make an Herb-infused Oil Without Heat
This method is a lot like making a tincture, vinegar, or even an infused honey. You’ll need a bit of paitience and a glass jar with a tightly firring lid.
- Fill your jar with your dried herbs about a quarter to a third of the way. For resinous plants, you can aim for closer to a quarter full. For non-resinous plants aiming for a third full is wise.
- Fill the jar about three quarters of the way full with your oil.
- Stir the mixture with a stick, chopstick, or spoon to dislodge any stuck air bubbles. You want to avoid trapping air in your mixture.
- Top off the jar with oil once you’ve removed as much air as possible from the mixture.
- Seal the jar and let it stand in a cool, dark place for at least three weeks and as much as six months, shaking daily for at least the first two weeks or as often as you remember to do so.
- Strain the herbs from the oil. Discard or compost the herbs.
- Pour the oil into a jar or bottle with a tight-fitting lid and label it.
Storing infused oils
No matter how you made your infused oil, store it in a cool, dark place out of sunlight. If you do not intend to use it up quickly, you can store most of it in the refridgerator and keep a smaller jar of it on the counter or in any handy space. It’s wise to use an amber or colored jar or bottle if you will be storing it where it may be exposed to sunlight, including filtered sunlight. Infused oils can last for years under the right conditions. Still, it’s wise to make smaller quantities and use them up then make more rather than to make a huge quantitiy and let it stand for several years.