A medicinal oil is an infusion of plant material in oil. Oil infusions are a method used by Herbalists to extract the medicinal properties of plants. This method is used with all types of plant materials, but most often with flowers, leaves and stems.

Herbal Infused Oils are used to make:

  • Salves
  • Balms
  • Medicinal Creams
  • Ointments
  • Soaps

I use two different methods to make Herbal Infusions. My preferred method is the Sun Infusion, but I find the Water Bath method very reliable, especially during a cold, rainy and cloudy stretch.


Fresh or Dry Plants?

Fresh Plant Material

I most often use fresh plants for my oil infusions. When harvesting fresh plants, be sure to allow them to sit overnight to allow them to wilt slightly. This allows some of the moisture to escape. It also gives the many six and eight legged creatures a chance to escape. I usually spend quite a bit of time delivering insects back to the garden while my fresh gathered plants are wilting. Susan Weed’s book taught me to ‘fill my jar twice’ when using fresh plants. Once with the plants and second with the oil.

Dry Plant Material

Dry plant material is effective as well for oil infusions, but the ratio is much less. I use a 5:1 ratio of oil to plant material. (5 parts oil to 1 part plant material). I do this by eyeing it up rather than measuring in a strict manner. Sometimes, depending on the particular dry plant I am using I may increase the amount to up to half the jar, especially if it is very loosely packed.

Both Methods Begin the Same Way:

To make an oil infusion it is very important to sterilize all your equipment. I sterilize my jars and utensils in the oven at 180 for 30 minutes.

When using fresh plant material, I follow the folk method for measuring. I admire many old traditions from the past. Sometimes I imagine a person making medicine 500 or even thousands of  years ago without scales or measures as we have today. These ‘folk methods’ of measuring have always been effective and have never let me down.

If you are using fresh plant material, you simply fill your jar loosely with chopped plant material. Do not pack it down. Then fill your jar again with your oil of choice. I recommend using a food quality, certified organic oil. My favorite oil to use is Olive oil, but many carrier oils are suitable for herbal extractions.

Fill your jar up to an inch below the rim. Cap your jar and label clearly. I find it best to put two labels on the jar; one on the lid and the other on the side.

Making Med Oil Post

St. John’s Wort flowering tops

Sun Infusion

The Sun Infusion requires much more care than the double boiler/water bath method. For me it is a labour of love. Daily attention is required to ensure a success.

Place your jar in a sunny spot outside. My porch is lined with bottles all summer long.

Every day, remove the lid and with a clean, dry tissue wipe the bottom of the lid until it is dry, then dry the inner rim of the jar.

I hold the tissue so that it goes into the oil slightly to be sure I get any and all moisture off the rim.

Sometimes you may see water droplets on top of the oil. Use a clean tissue to dip directly into that spot. The tissue absorbs the water so well.

Once the lids and rims are sufficiently dry and the lid is tightly back in place, hold your jar upside down and shake it around.

Repeat this process daily for 4-6 weeks. If it rains, bring your jars inside and keep them in a warm place. If it gets cold and there is no sun for an extended amount of time, you can put your jar in a water bath at a very low temp to continue the infusion.

Water Bath Infusion

Place your jar containing the oil and plant material in a pan of water. It is very important not to let the temperature of the oil exceed 110 F. Over heating will destroy the valuable properties of the plants and your oil will not be effective. You can buy a thermometer at your local hardware store to keep track.

Also, be sure to keep a close eye on your water level. Keep it up high to cover the jar as much as possible without letting the water rise to the rim. If the water gets low, the temperature of the oil will rise significantly.

I use a deep cast iron pan for my water bath and I also use an industrial chafer. A crock pot can be used as long as you can keep the temperature low enough. Use your thermometer to be sure!

People say a water bath infusion of 3 hours is long enough to extract the medicinal properties. If you need your medicinal oil immediately this should do, but I let my water bath oils infuse for a couple of weeks at a steady temperature.

When your oils are sufficiently infused, use a sterilized tea strainer lined with cheese cloth to strain your oil into another sterilized mason jar. I pour off most of the oil and then allow the jar to sit upside down on top of the other jar to let the oil drip off. Then you can use a sterilized spoon to squeeze the last bits of oil through the cheese cloth.

Cap your oil with a clean lid and label your jar with the name of your oil and the date.

Herbal infused oils can be stored for about 18 months in a dark, cool place. You can add vitamin E or essential oils to help preserve the infused oils longer. Jim Mcdonald mentions an old text book he came upon which said that adding Slippery Elm bark to Oil Infusions extend the shelf life considerably.

Resources, References, Inspiration

Gladstar, Rosemary – Herbal Healing For Women

Gray,Beverly – The Boreal Herbal 

Mcdonald, Jim – www.herbcraft.org/slipperyelm.html

Ode, Penelope – The Complete Medicinal Herbal

Weed, Susan – Healing Wise