Tree Bark medicine

By Jen Costa

Whittling black birch bark

Whittling black birch bark

Whittled black birch bark showing pale green cambium layer where medicine is stored

Whittled black birch bark showing pale green cambium layer where medicine is stored

Fall is traditionally the season for bark harvest and it may be one of my most satisfying medicine making tasks. It requires I lean into my relationship with a tree and these relationships are different than with smaller herbaceous plants. Yes, we can have different relationships with and honor the plants, trees, animals, insects, people, and even the elements, landscapes, and microbial world.

The task of whittling bark with my sons over the years has always been enthusiastically received.  When whittling, the mind also enters that hypnotic, trance-like state of being, much the way gazing at a fire captivates us to higher thinking. The therapeutic medicine is already working just by being available to such a connected, receptive state. Rushing about, task oriented, with a connection to time that is stressed and manic will never produce a medicine nearly as potent as one made with the process honored. Seeking connection to the trees is the beginning. What I speak to here is knowing how to find, tend, intuit, harvest, and make good medicine that can live near you, in your home apothecary.  

Let's Talk Bark

What is bark to you? Some describe is as being like our skin and this is in some ways true. Bark is constantly growing and changing based on the needs of the tree and the influence of its surroundings in the local environment. We can see this within the rings of the tree and how widely spaced or close together they are: scientists study this fingerprint of the weather the tree has endured.  Elevation changes how trees grow as well, and they are smaller and smaller with higher elevations in some regions.

Interacting with the world around them determines what strong chemical constituents a tree will make. We make medicine from the plants, or in this case the trees, that make chemical compounds to ward off insects, disease, sun damage, and other elemental and environmental exposures. Their protective medicine made for their health is what we take in to stimulate our bodily processes. It's so simple but still full of such magic for me: that we can literally be this connected to the plants and trees. 

Trees are part of a network system within a forest and so their very design includes interacting within community as a way to thrive and protect themselves and make strong compounds along the way. Bark contains the growing cells of the tree, as well as the cells required to transport water and sugar for photosynthesis on a cellular level. Bark is always interacting with the rest of the tree, the surrounding trees, the mycorrhizae in the soil, and is constantly reading and responding to any changes in its surroundings.   

So just under the thick outer bark is the layer we seek for medicine making. The outer bark is not the place to harvest for this is a hardened protective coat. We are seeking the cambium layer that is the alive and actively responding part of the tree. It can be white, green, yellow, even pink, and is generally smooth, moist, and clearly alive as a thin layer of active cells that surrounds the entire tree just under the tougher outer bark. 

What is Ethical Wildcrafting?

"Ethical Wildcrafting' was a term coined decades ago in the herbal medicine world and is the practice of harvesting plants and trees conscientiously, to avoid damaging the health of the population or the overall ecological system they thrive in. It’s especially important here because if you don’t harvest bark properly, you will literally kill the tree. The basic principles of harvesting are simple:

  • Harvest so the tree can live and thrive too – otherwise seek a different medicine
  • Harvest only what you truly need - the rule is to harvest enough to get the next harvest season

The most common way to kill a tree fast and efficiently is by ‘girdling the tree’, or removing a section of bark around the entire circumference of the trunk of the tree. Please do NOT remove bark all the way around the base of the tree like this. Girdling kills the tree because the leaves and roots can no longer connect and transport water, nutrients and sugar between the tree top and roots. This leaves the tree to starve to death. i
We're being asked to think in terms of the ecology of restoration instead of consuming and taking. 'Having enough' is built into the restoration way of being. 

How to Harvest Bark

Tools & Timing:

  • Pruners, saw, pole pruners are great for reaching high
  • A small, sharp straight edge knife
  • Towels or sarongs to drape over the lap of the whittler to catch the shavings

Harvest bark when the nights become cool, the days are warm and crisp, and the leaves are changing color and just starting to fall. You want the tree’s energy to be focused on shunting all of its activity down to the Earth for winter. This concentrates the medicine into the moving part of the bark we spoke of called the cambium layer.


What Tree is Calling You

Wild cherry bark is a traditional lung remedy

Wild cherry bark is a traditional lung remedy

Common species that make great medicine include White Willow, Wild Cherry, Witch Hazel, White Oak, Sassafras, Black or Silver Birch, Black Haw, White Pine, Cedar, Juniper, Hemlocks, Spruce. It’s wise to also find the trees you are seeking medicine from in the early fall so you can positively identify them when they still have leaves. As you spend more and more time with the trees, you will know them from the bark which is always quite unique. Once your tree is located, simply return when the time for harvesting arrives. Choose a smaller tree so you can reach the branches or get a pole pruner. These scouting trips are part of your connection, relationship, and honoring of the medicine within the bark of the tree that calls. Be aware to never harvest on state lands at all or other's property without permission.

While scouting and finding your tree, do taste the tree. Cut or pinch off a little twig, after intuiting a sense of permission and affirming this is ‘the tree’ I seek. Chew on it until you get a good sense of the flavor. Then spit it out if need be. With a little experience, you’ll be able to tell how strong the medicine will be from this tree. Even if you’ve never tasted this medicine before, know that strongly medicinal barks will affect your mouth almost immediately. Willow and Witch Hazel suck up all the spit in your mouth (astringent), sassafras makes your mouth feel watery and slippery,(demulcent), black birch tastes like root beer or wintergreen for some (aromatic), Wild Cherry tastes a bit nasty but is identifiable as such, Pines taste just like the sap smells (aromatic) and these essential oils travel quickly up through your sinuses and down to your lungs. If you don’t notice anything, even if you don’t know what it should taste like, move on and be sure to only make medicine from a tree you absolutely know.

If you’re not routinely tasting the plants you harvest, i suggest getting into the habit. This is one of the skills of an herbalist for testing quality, just as you would use all your senses to choose vegetables or fruits. The medicine person does the same for evaluating the medicine. Medicinal content changes throughout the season and from year to year, based on where each tree is in its growing and reproductive cycle, and what its life has been like this year. This is true for smaller herbaceous plants too. If a particular tree isn’t strong enough this year, come back next year and see what it says to you.

Time to Harvest

Witch Hazel-Hamamelis virginiana

Witch Hazel-Hamamelis virginiana

So now you’re sure you’ve got the right tree, and it tastes great (or terrible) so you know it’s got some magic and good medicine in it.  Next I offer a gift to the tree. This a traditional way of working and you can decide what works for you. A moment of silence, a song, a prayer, some of your lunch or water, or a handmade something that honors the tree you are taking medicine from. 

The next step is to harvest the bark. Choose a small branch, maybe the size of your wrist or smaller. Find a place where the branch branches, then identify the collar, or the fatter part at the base of the branch. Use your pruners or saw to cut the branch just beyond the collar; if you cut into the collar itself, the tree won’t heal well and could rot from microbial invasions at the site. Make your cut parallel with the collar, so water won’t collect in the cut. Don’t let the wood split or crack, cut it cleanly so you don’t hurt the part of the branch you’re leaving behind; if necessary, cut part of the way through from the bottom up, then finish by cutting from the top down. Remember that the priority is to not hurt the tree: don’t take more than the tree can spare, don’t take more than you can use, and don’t make cuts that will hurt the tree long term.

For smaller quantities needed because you know a large branch is too much,  cut thumb-sized branches and estimate how many to fulfill your needs. You get better at this estimating with time and practice. 

Time to Whittle

Bring the branches to your place in the sun, or like me here, bring inside by the fire if it's too cold out for you. Look them over carefully and wipe off any dirt, lichen, insects etc. Use the pruners to remove tiny twigs and pile them up for they’re medicinal but you don’t need to save them unless you have a use for them. I often add pine needles to my bark preparations, just for the record. So now you can cut the branches into smaller pieces at this point to make them more manageable, 1-2 foot sections work well. When you’re ready to whittle the bark, sit with one end of a branch in your non-dominant hand, and the other over your lap in front of you. Use your knife to whittle down the length of the branch, always working the knife away from you so there are not accidents, removing long strips of bark. You want to make sure you get the cambium layer, the inner bark that contains all the good medicine, but not the wood. Remember, the cambium can be white, green, yellow, or pink, and is generally smooth, moist, and clearly alive. If you’re shaving off wood, make your cuts shallower; if you’re leaving the cambium on the wood, go back and shave it again. If you’re struggling to shave the bark, try switching knives because sometimes a different size, shape, or well sharpened blade does the trick. When you’re done, the branch should be all wood with no bark visible. Unneeded parts make good kindling for the fire. 

Making the Medicine

To make bark medicine, you can tincture it fresh in alcohol or vinegar, infuse it in olive oil for topical uses, or dry it for later uses of bathing, teas and decoctions, or syrup making.

Drying Bark: Spread the bark in a single layer on a drying rack in a cool, dark place, and stir regularly until dry, a few days to no more than a week. Even better is a dehydrator. Once it’s dry, store in jars, or bags away from light and well labeled. Dried bark is useful for teas and decoctions, ground into poultices.

Fresh Bark Tincture or Vinegar: Bark, because it is so fibrous and dense, needs more liquid to extract all the medicine so fill your jar with the fresh whittled bark and don’t pack it too tight. Most barks prefer lower alcohol content, too, so use 40%-50% alcohol (vodka or brandy work well). Next fill the jar with the alcohol or vinegar and cap tight and shake. Label well with the common name, latin name and date. Shake a few times per week, store away from direct light and you can strain and use after two months. It will keep for more than 10 years.  

Dried Bark Tincture: I fill my jar 1/2 full with dried bark i. Then fill with  vodka or brandy or warmed vinegar, cap and shake a few times per week for 2 months, labeled well. Strain, re-bottle and label for use. 

I hope you decide to give this a try! It’s so easy and satisfying, especially in the dead of winter when you clear up that cough with your own White Pine Bark vinegar or tincture, or help a brutal headache with White Willow Bark you made yourself with the tree right outside your window that you love deeply, or eased postpartum swelling or hemrroids with a Witch Hazel Bark sitz bath. I love hearing your successes and failures with medicine making as we all learn equally from both.

Trees of Life

Jen Costa sitting with one of the guardian White Oaks that forms a circular grove around her home in Woodstock NY. Part of her work includes being a Community Herbalist, Earth Medicine Practitioner, Critical Care Nurse, and founder of ElderMoon School of Herbs & Earth Medicine. The ElderMoon Apothecary has been birthed!  This continues to grow with handcrafted herbal remedies for supporting wellness close to Nature and helps to guide the training of herbal healers both live and on-line through herbal infused courses and journeys with Nature. Information & Website: