Walnut - Juglans Spp.: Edible & Medicinal Uses of a Highly Prized Wild Nut Tree

Edible Uses of Walnuts
Medicinal Uses of Walnuts
Alternative Uses of Walnuts
Growing Juglans Species
Warnings

In Ontario, black walnut (Juglans nigra) and butternut AKA white walnut (Juglans cinerea) are our native walnut species. Around Haliburton we’re barely in range, with only a few black walnuts and butternuts noted on iNaturalist. Both species are more abundant to the south. There are a few nonnative Juglan species around Ontario too.

As a pioneer species, you can find walnut trees in clearings that are starting to turn into woods, perhaps with some black cherry and red maple. Our two species look alike and can be distinguished by their terminal bud for one. Walnut has a grey terminal bud, and butternut yellow like butter. Walnut has light tan pitch and butternut a dark brown pitch. There are also subtle differences in their leaves, bark and fruit. Around here there are no poisonous lookalikes. It’s possible to mistake the leaves for a shrub like staghorn sumac or a cousin like hickory.

Walnuts - Juglans Spp. — *Walnuts – Juglans Spp.*

Edible Uses of Walnuts

Similar to hickories, walnut kernels are a highly desired traditional wild nut. The only downside to walnut trees is they take over a decade to mature and fruit, the trees don’t fruit every year, and the older they get the more irregular their fruiting is. Then again, if you have mature trees you’re going to have a bountiful harvest every few years!

The nuts can be picked off the ground in autumn. Wear gloves to handle them to avoid having your hands dyed black for a time! Grind or smash the soft hulls off using your shoes or other means such as a knife. If the hulls are damp, you can lay them in the sun to dry them off. If they are dirty, you could power wash them first! Just make sure to hull them promptly, or they may mold. Then leave the shelled nuts to cure for 2-3 weeks before cracking the shells. Some folks like to cure them for months for added flavour.

Walnuts are notoriously hard to shell, but worth it! A hammer works. Pliers and a nutpick can help of course. Some places have a local “hulling station”, although I’ve never heard of one around Haliburton. The nuts store best in a freezer.

Walnuts of course are used in many ways from baked goods to tossed in salads. Same as the nuts you’d buy in the grocery store.

You can also skim off a nut oil, or grind the nutmeat with honey or herbs for a nut butter.

The trees can be tapped around early spring and the sap processed just like sugar maple.

There are a few more or less obscure uses. Immature fruits with the husk can be used in the summer to make “nocino”, a walnut derived liquor. Russians use walnut for a regional jam. Some folks pickle immature walnuts husk and all.

Butternuts are used similarly. Black walnut is more comparable to what you get in the stores.

High in manganese, antioxidants and omega 3 fatty acids. Walnuts are also touted as a superfood for health goals like reducing cholesterol.

Medicinal Uses of Walnuts

Walnut is primarily said to support these body systems:

Digestive
Integumentary

Medicinal tags include Alterative, Anthelmintic, Antibacterial, Antifungal, Antiseptic, Astringent, Cathartic, Laxative, and Purgative. See Medicinal tag key for more information.

Common usage includes the green outer layer of black walnut bark used in an infusion as a gentle laxative. Perhaps combined with ginger for its carminative properties. Walnut is comparable to rhubarb as a mild laxative. It’s also well used for typical astringent purposes e.g. mouthwash and skin washes.

A bark decoction of either black walnut or butternut is used to kill worms. It is one of the safter purgatives for worms. It’s similarly used for fungal infections like athlete’s foot, acne and cradle cap. Gut infections like SIBO may respond to walnut as well. Do not try this if you are pregnant or breastfeeding.

Juglandin is its main medicinal component for all the above.

The leaves are used for some pharmaceutical ingredients including plenolic acids.

Alternative Uses of Walnuts

Perhaps the most famous use of black walnut is the tannin-rich husks for tanning or for a brown to black dye. For dye, I documented Robin’s first adventure in making and using black walnut dye previously. It’s definitely a natural dye you’d want to read up on before trying! Butternut is also used for dye. Butternut inner bark makes a purple dye.

Black walnut is a highly desired wood for everything from flooring to woodworking.

The hulls can be ground finely and are used as an abrasive in various products.

The nut oil is used in some soaps, paints and other products.

Juglone is a natural herbicide. The highest concentration of juglone is in the roots. Planting near these trees can be tricky because of this!

Growing Juglans Species

These slow-growing trees like full sun and well-drained soil. As a companion plant, wild ginger (to be covered January 2026) thrives under black walnut trees. Some experts recommend planting alder near the base of a walnut tree to help it grow (the alder will eventually die off). The trees will begin to bear nuts in about 12-15 years.

Many birds, mammals and insects use walnut trees for food or shelter. Walnut is also host to the larvae of the banded hairstreak (Satyrium calanus falacer) butterfly. And squirrels are one of this nuts biggest fans! They are the wildlife species that naturally plants the most walnut trees.

“Walnut caterpillar” moths also have caterpillars that love this tree, and cuckoo (Coccyzus spp.) birds love to eat these cats. Cuckoos like to nest in wild grapevines too, so there’s an idea for people who want to attract this rare bird! Walnuts and wild grapevines!

Thousand cankers disease is spreading and killing these trees; something to take note of, especially if you are further south in Ontario. Here’s more info to help you keep an eye on your trees.

Warnings

Internal medicinal usage is not safe for those who are pregnant or breastfeeding.

Not for prolonged use medicinally.

And the Usual Cautions:

1) Most medicinal herbs, if edible, are meant to be eaten in moderation, even sparingly. Some require extra preparation. Tannins are toxic if consumed in excess. Before taking any new supplements, you should consult with a healthcare professional.

2) A vast amount of these herbs are diuretic. (See the Medicinal tags above to check if this featured herb is one of them!) Diuretics are generally safe, but they can be risky for people with other medical conditions or who take certain medications. Please consult your doctor if you have any health conditions.

3) People can be allergic or sensitive to nearly any plant; try new herbs one at a time at your own risk. For instance, saponins commonly cause stomach upset.

4) For serious medicinal use, I must recommend receiving a diagnosis and working with a reputed health care provider. I generally do not post specific treatments and dosages because I think that is best between you and your health care provider, and ideally monitored.

5) Anyone pregnant, nursing, or taking prescription drugs should talk to a health care professional before adding new food items to their diet.

6) Many plants have look-a-likes, and sometimes they are poisonous.

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REFERENCES

My new favourite foraging book is Sam Thayer’s Field Guide to Edible Wild Plants: of Eastern and Central North America (The Sam Thayer’s Field Guides) Paperback – June 1, 2023 and this plant IS featured as one of the edible wild plants in this area. I highly recommend this guide for your bookshelves!

https://data.canadensys.net/vascan/taxon/6243

https://www.illinoiswildflowers.info/trees/plants/black_walnut.htm

https://en.wikipedia.org/wiki/Juglans_nigra

Edible and Medicinal Plants of Canada

Stalking The Wild Asparagus (Field Guide Edition).

The Herb Book: The Most Complete Catalog of Herbs Ever Published (Dover Cookbooks)

How Indians Use Wild Plants for Food, Medicine & Crafts (Native American)

Indian Herbalogy of North America: The Definitive Guide to Native Medicinal Plants and Their Uses