This article is an excerpt from my course about using herbs and herbal products, including essential oils, in the home or professional apothecary. If you'd like to be notified when the course next opens for enrollment, please sign up for my email newsletter at the end of this post.
If you ask three different herbalists how they each infuse their herbal oils, you'll probably hear about three different processes in response. We all have our own unique way of transforming our plant material into apothecary formulas and compounded recipes and I believe it is so valuable to learn from several different people and then develop our own way of doing things. I am often asked about how I like to infuse my own herbal oils, so I thought I'd share an excerpt from my upcoming course with you today. It covers everything you could ever need to know about infusing herbs into carrier oils. The techniques I've outlined below can be used for a wide variety of herbs, but I'll be using Calendula as an example and we'll be focusing on herbal oils for topical use. (I've also written about infusing St. John's Wort oil in this post from 2016.)
the THREE main TECHNIQUES
The "It Takes Time" Method
This is my favorite way to make herbal oils. It takes time and patience, but the result is such a beautiful, happy infused oil (and I'm able to use more delicate and lightweight carriers) that I really prefer it to the quicker methods. To make an infused oil this way, you would fill a sterilized glass vessel 1/2 to 2/3 of the way with the herb of your choice, then pour your carrier oil of choice (more on carriers further down in the article) over the plant material until it's completely covered, with an inch or so of extra oil to top it off. The herbs will often move around in the oil or float to the surface of the oil. This is fine. Use a chopstick to move through the herbs to release any air bubbles and top off the jar with more carrier oil if needed.
Secure the lid of the jar (standard lids are better than plastic; the plastic lids will leak when making herbal oils) and allow the herbs to infuse in the carrier oil for 4 to 6 weeks. Many herbalists will turn the jar upside down every day or two or give it a little shake, but I've found that it's not necessary and can tend to make more of a mess than anything.
Once your oil has infused for 4 to 6 weeks, you can strain the herbs out of the oil through a couple layers of cheesecloth and a fine mesh sieve, making sure to squeeze all of the extra oil out of the fabric when you're finished pouring the oil through it.
Store the infused oil in a sterilized glass jar with a pretty label containing the name of the carrier oil you used and its expiration date, along with the herb(s) you used and the date you harvested them (or the date they were harvested by the person from whom you purchased them), and the date you strained the oil.
The "Low and Slow" Method
A crockpot / slow cooker can also be used to make herbal infused oils. This method is often employed when the herbal oil is going to be needed sooner than 4 to 6 weeks, but not necessarily that very day, or when the herb is especially resinous and might need a little bit of heat to efficiently extract the resinous compounds. When using the crockpot method, I recommend choosing a carrier oil that does well when exposed to higher temperatures, such as avocado or coconut oil. Place your herb(s) into a clean slow cooker and cover them with the carrier oil. Set the heat to the lowest setting and leave uncovered, stirring occasionally. You don't want the slow cooker to become hot enough to cook the herbs into the oil, but you do want it to be warm enough to infuse the oil with all that herbal goodness fairly quickly.
Some herbs will only take a couple of hours to infuse this way, while others may take one, two, or even three days. Keep an eye on the oil and check it often. As soon as the oil looks and / or smells like it's finished (the color might change; the oil will take on the aroma of aromatic herbs; etc.), turn off the heat and allow the oil to cool completely before handling.
Tip: You can use the "It Takes Time" method to infuse your herbal oil, then after the 4 to 6 week infusion period, you can finish off the oil with an hour or two in a slow cooker (at a low temp) to better extract resinous compounds from resinous herbs.
Once the oil has cooled, strain and store it as described above.
The "I Need It Now" Method
Sometimes you just need an herbal oil right away and even if you prefer to take your time when making them, you might need to make do with what you have available in the moment. In such circumstances, there are often alternatives to herbal oils - could you use a poultice, compress or soak instead or in the meantime? When an herbal oil is the solution, however, you can use this stove-top method to make a quick herbal infused oil.
Set up a double boiler over low heat. Your herbs and carrier oil (use one that will tolerate higher temperatures well) will be placed in the part of the double boiler that does not come into contact with your heat source. Make sure the herbs are covered with the carrier oil. This method may take 30 minutes to a couple of hours and since you're working with oil, you'll want to make sure to stay nearby where you can keep an eye on it. You don't want the oil to become so hot that the herbs start cooking and you need to make sure the water in the double boiler does not run dry. Once you feel that your oil is ready, turn off the heat and allow the oil to cool completely before straining and storing as described above.
I don't personally recommend using the stove-top method regularly. It's best suited for those moments when you really need a specific oil on that day, but you've just run out of your last batch and haven't had time to start a new one yet. In most such cases, though, you'll be able to substitute with a different application method using the same herb, as I mentioned earlier. This method works in a pinch, but yields an inferior (though usable) product. Others may disagree, but my preference is to use the "It Takes Time" method whenever possible; the "Low and Slow" method when I need something right away; and the "I Need It Now" method only when absolutely necessary (and I've very rarely found it absolutely necessary).
double and triple infusions
Double and triple herbal oils can be made using any of the above-mentioned methods. To make a double or triple infused oil, you would strain out your initial batch of herbs as described, then pour that same batch of oil over a fresh batch of the same herb and then allow that second batch of herbs to infuse in the oil as you did with the first batch. The process can be repeated again a third time to make a triple infused oil. Such infused oils are stronger and more potent than once-infused oils and are often preferred for first aid applications and some skin care remedies / formulas or when an aromatic herb is being used and the formulator wants the infused oil to smell strongly of the herb being used.
SINGLE HERBS OR BLENDS
I'm often asked if it's better to infuse herbs into oil singly or in pre-combined blends (i.e. Lavender and Calendula infusing in the same carrier oil in the same jar at the same time). Honestly, it doesn't make much difference. The best choice is the method that will work best for you. I prefer to infuse my herbal oils individually and mix them later so I have more options when it comes to formulating, but if you have limited space, you may prefer to infuse oils with a combination of herbs at one time. There are one or two blends that I do infuse all together and I believe a nice synergy can be achieved this way, but I think intention makes more of a difference in such cases than does infusing the herbs on their own or together. Try infusing your oils both ways and go with the method that you enjoy most.
FRESH OR DRIED?
There are certain herbs that are best when infused into oil fresh. St. John's Wort is a classic example of this. The hypericin (the compound in the herb that turns the oil red) is one of the main constituents you're after when infusing St. John's Wort into oil and you won't be able to extract it if you use dried plant material. (This is why herbal oils made with dried SJW or SJW that was harvested at the improper time don't turn red.)
Most other plants, however, are best infused into oil with dried plant material. Using freshly dried herbs will keep your herbal oil from developing mold and spoiling. If you're working with fairly "dainty" herbs (think lightweight, thin leaves and flowers), you can choose to infuse them fresh, but you'll want to let them wilt in a shady spot for a few hours (up to overnight) before placing them into the oil. Never place freshly washed herbs with residual moisture on them or herbs fresh with dew into a carrier oil.
Thicker plants like Calendula flower heads or Dandelions shouldn't really be infused into oil fresh, since they hold so much moisture in their inner bits that you'll rarely be able to achieve a finished oil without it spoiling. It's best to allow them to dry completely before infusing.
WHICH PLANT PARTS?
The plant part used to make an herbal infused oil depends on the plant you're using. Usually, the plant part(s) that you would use to make an herbal tea, compress, poultice, or essential oil is the part that you'll use when making an herbal oil. The main thing you're after is the plant part that has the constituents / therapeutic effects that are particularly beneficial for the skin.
Which carrier oil?
I'm often asked which carrier oil one should use when making herbal infused oils. Extra virgin olive oil has traditionally been used for salves in the herbalism field, but it's quite heavy and does have a very distinct scent which might not be desirable in your finished product.
Overall, any carrier oil can be used to make an herbal infused oil. Personally, I tend to choose a carrier oil that has similar therapeutic properties to the herb that I'm going to be pairing with it and one that I like to use on my own skin. I look for carrier oils that are organic, fair trade (as local as possible), cold pressed, virgin and unrefined. I don't like to use processed / refined oils in my recipes. The main thing to avoid is mineral oil, which isn't a carrier oil at all; it's a petroleum-based product.
to blend or not to blend
Some herbalists will place their herb into the blender with a bit of carrier oil and give it a rough chop before pouring it into the jar to start infusing. This is optional and can be a nice step for some herbs, like Calendula, but it isn't always necessary. The theory behind blending the herb first is that you're creating more herb surfaces that will come into contact with the oil. Some herbalists swear by this method, but I don't usually do this because...let's be real...cleaning carrier oil out of a blender is kind of a pain. ;)
Sunlight or Darkness
While it's true that sunlight can contribute to oxidation, many traditional and folk herbalists swear by letting their herbal oils infuse in sunlight. St. John's Wort oil is still one of the main herbal oils that is allowed to infuse in the sunlight of bright windowsills around the world. Yet other herbalists insist that herbal oils be sequestered in a dark cabinet and kept away from the light whilst infusing. Which way is better? The way that feels best to you. If you want to infuse your oils in a dark cabinet, go for it. (I especially recommend this when infusing with carriers that tend to have shorter shelf lives or need refrigeration.) If you want to infuse your oils in the sunlight or the moonlight, go for it. I really think it's a matter of personal preference. You will want to store your finished and strained herbal oils away from sunlight, however.
HOW LONG TO INFUSE
Herbal oils that are made with dried plants can be infused indefinitely, though the standard time is 4 to 6 weeks. The main thing to be aware of is the shelf life of your herbal oil. Oils that are infused longer than 4 to 6 weeks won't necessarily be any better or more potent than oils that are infused for 6 weeks, however, because most of the constituents will already be in the oil by that time.
The main reason people allow their oils to infuse longer than 6 weeks is that they've forgotten to strain them. If that's the case for you, don't worry. Your oil is fine. Just strain it when you have a moment so you can start using it. =)
There are a number of ways you can enhance the subtle effects of your herbal infused oils, but two of my favorites are to infuse them alongside the moon's natural waxing and waning cycle and to nestle the jars in with crystals and minerals. While not appealing to everyone, I find that these two things can really be lovely complements.
Personally, I like to start my herbal oils on the day of the new moon and strain them on the following full moon, which is usually about 6 weeks later, when nature's energy is the most potent and lively.
Some of my favorite stones to use when making infused oils are rose quartz, black tourmaline, amethyst and selenite. The rose quartz brings a vibration of love and an open heart, whilst the black tourmaline and selenite are protective against negative energy and EMF influences (I still recommend keeping your apothecary items away from wifi and electronics, however), and the amethyst is a well-loved all-around healing stone.
Fun Fact: My husband and I have been collecting and selling crystals and other rocks and minerals for many years. One of our favorite together-hobbies is sourcing new pieces and keeping our online crystal shops stocked. =)
As a person of faith, I also like to pray over my herbal oils as they're infusing and thank the Creator for providing the plants whilst asking for the finished product to be blessed for the healing of those who will need it.
how to use herbal infused oils
Once you have an herbal infused oil that's been strained, there are many ways you could use it. Herbal oils can be used alone, without having to be altered or added to anything else. If you want to use them on their own, I recommend applying them when you're fresh out of the shower after toweling dry or after washing and drying your hands. Applying herbal oils to freshly washed skin helps them to soak in quickly and will prevent them from leaving an oily, persistent residue on your skin. It's best to wait until the oil has completely soaked into your skin before putting on clothing items to avoid staining them.
Herbal infused oils make lovely bases for massage oils and can be used on their own or combined with other carrier oils and / or essential oils.
Herbal oils can also be used in recipes for salves, balms, ointments, creams, lotions, and butters wherever a carrier oil is called for as an ingredient. This is one of my favorite ways to layer the therapeutic effects of my ingredients into a product. For example, instead of just using olive oil in a salve that calls for it, use olive oil that's been infused with Calendula, Plantain leaf (Plantago sp.), and Lavender buds to add an extra layer of therapeutic benefits to your finished salve.
which method(s) DO YOU (or would you) LIKE TO INFUSE YOUR OWN HERBAL OILS? I'D LOVE TO HEAR ABOUT YOUR OWN PROCESS IN THE COMMENTS BELOW!