Infused oils are a foundational cornerstone of herbal-powered wellness products such as salves, creams, lotions, serums and other topical formulations. Oil acts as a solvent (aka menstruum) to capture oil-soluble plant constituents such as alkaloids, gums, resins, volatile oils, and certain oil-soluble vitamins (A, D, E, K), allowing the plant’s therapeutic compounds to be delivered to the skin.
Before you begin, it’s important to make certain that the oil or fat you’re working with is high quality — preferably organic and cold pressed. Oils such as almond, olive, jojoba, tallow, lard, avocado and coconut are good choices, depending on your specific formulation goals. I personally gravitate toward more saturated and mono-unsaturated oils for their superior stability and resistance to rancidity, but you can also add antioxidants such as vitamin E to less stable oils to improve their lifespan.
The quality of your herbs are just as important as the oil. Organic herbs from trusted sources such as Mountain Rose Herbs or wildcrafted herbs from clean, unsprayed locations are a must. Thanks to their particular oil soluble constituents, some of the herbs that lend themselves to being infused in oil are:
- arnica
- burdock (root)
- calendula
- cayenne
- chickweed
- chamomile
- comfrey (leaf & root)
- cottonwood buds
- dandelion
- elder (flower)
- frankincense
- gotu kola
- lavender
- lemon balm
- marshmallow root
- meadowsweet
- mullein (flowers & leaf)
- myrrh
- nettle (leaf)
- Oregon grape
- peppermint
- plantain
- rosemary
- self-heal
- St. John’s wort (flowering tops)
- thyme
- yarrow
Fresh or dry?
The next thing to consider is whether you will be infusing fresh or dried herbs. For most herbs, you’re going to want to use dried to avoid the risk of mold and bacteria contaminating your oil. St. John’s wort, mullein and cottonwood buds are a few exceptions to this rule. If using fresh herbs, it’s a good practice to wilt them overnight first, to let some of the moisture evaporate out of the plant.
Making a warm (or solar) maceration
There are a lot of different methods used to infuse oil, and every herbalist seems to have their own preferred way of doing things. Some herbalists are sticklers for measuring/weighing everything. I’m not one of those. I typically use the “fill the jar half full of herbs, then fill the rest of the way with oil” eyeball method. As you can see, it’s very scientific. This also sometimes referred to as the “folk method” for making herbal medicine.
If your herbs are on the larger side, crush them with a mortar and pestle or give them a quick trip through a coffee grinder to expose more surface area. Don’t grind them too finely, though, or you’ll have a rough time straining your oil later!
Fill a clean/sterilized jar with herbs to the halfway point, and fill (almost) to the top with oil. Make sure all of your herbs are submerged in the oil. Secure the jar’s lid and wrap with a densely woven dish towel or enclose it in brown paper bag to keep it out of direct light. Place in a warm location in your home such as a windowsill for at least 6-8 weeks (longer is better). Turn the jar on its head or give it a shake every day or two for the first few weeks.
When the infusion is complete, strain out the plant material (aka marc) using a fine mesh strainer, coffee filter or cheesecloth. This method is sometimes called a warm oil infusion or a solar infusion and it’s about as simple as it gets — it just requires a bit of time and patience.
Hot oil maceration
Tallow, lard, coconut oil or any oil that is solid at room temperature will require an infusion method that keeps the oil liquid for the infusion period. This is known as a hot oil infusion. A mini slow cooker or Instant Pot on the yogurt setting works great for hot oil infusions. The low heat speeds up the infusion process, and your oil will be done in days instead of weeks/months. Simply fill your cooker with your oil of choice and set it on warm (NOT low); you don’t want the oil to get much hotter than 120F. If you’re using a solid oil, wait for it to melt before adding your plant material. Again, I don’t typically measure here, but aim for roughly twice as much oil to herb by volume.
Another clever way to do a hot oil infusion is to use glass mason jar and place it in a warm oven or dehydrator cabinet (the type you can remove the shelves like an Excalibur) at 100-120F. This is my preferred way to do smaller batches of oils where even a mini crockpot would be overkill.
Once again, different herbalists have all sorts of different recommendations for how long the oil should be infused. 8-12 hours or overnight is common. The Herbal Academy recommends 4-8 hours (or more). Richo Cech recommends a whole week for fresh herbs or 2 weeks for fresh St. John’s wort. Crack the lid of the slow cooker to allow moisture from the fresh plant matter to evaporate during the infusion process. For dried herbs, Cech recommends a 2-week infusion in the slow cooker. Personally, I usually stop after 48 hours or so, unless I’m looking for a particularly potent infusion.
Whatever method you choose to follow, when the time is up, turn off the crockpot and allow the infused oil to cool slightly. When the temperature is comfortable to work with, use a fine mesh strainer or colander suspended over a glass bowl to separate the oil from the marc. Use the back of a spoon to the press the plant material and squeeze out as much of the precious infusion as possible.
Cool hot oil infusion hack
In his book Making Plant Medicine, Richo Cech offers an inexpensive “hack” to a crockpot with no warm setting or if you’d like more control over the heat settings. His suggestion requires a bit of electric know-how, so have someone comfortable with wiring to do this for you. A basic dimmer switch from the hardware store can be wired into your crockpot plug and voila, a simple way to fine-tune your heat source beyond the basic “low,” “high” and “warm” settings. I have not tried this myself yet, but these inexpensive plugin dimmers should accomplish the same thing, minus the need for an electrician. You just need to be mindful that you don’t exceed the wattage limits — in this case 300W — which should accommodate most basic crockpots (but not an Instant Pot, which is considerably higher wattage).
Water bath
Another alternative if your crockpot doesn’t have a warm setting, is to do a hot water bath. To infuse oil using a water bath, place your oil and herb into a glass jar covered loosely with a lid. Set the jar inside the crockpot on a trivet (or a few canning rings) to keep the jar from making direct contact with the hot crockpot vessel. Then fill the crockpot with water until it reaches about 1″ from the top of the jar of oil and herb and set your crockpot on low.
Storage
Store your finished oils in airtight glass jars kept in a climate controlled dark cabinet or closet away from sunlight. Your nose will likely tell you when your infused oil goes bad, but most herbalists agree that properly prepared fresh herb oil infusions will last about a year, while dried herb oil infusions will last up to 2 years.
DON’T.
FORGET.
TO LABEL.
THE JAR.
The name of the oil, infused plant and date are the bare minimum, even if you just jot the info down on the glass jar with a sharpie marker. It’s also helpful to record whether the plant was dried or fresh, and, if wildcrafted, location from where the plant was collected. Another suggestion is to record the intended purpose of the infusion (i.e. “mullein & garlic oil for earache” or “fresh nettle tincture for hay fever/allergies”) and any dosing information so you don’t have to look it up every time you use your preparation.
I can’t tell you how many times I’ve found a random jar of infused *something* with no label. At the time, I thought “I’ll label it later… I know what’s in there.” Trust me. In as little as a week, you probably WILL NOT remember what’s in that jar. Please label your jars. It’s so painful to have to throw away a precious infusion because you have no clue what’s in it.
I’m still hoping that if I hang onto these long enough, I’ll eventually remember what they are. Don’t be like me.
