Learn how to forage, identify, and harvest black walnuts (Juglans nigra) plus how to dry and cure the nuts, and use the hulls and leaves for remedies!
ID Tips for Black Walnuts
It’s fairly easy to identify a black walnut tree in autumn, when the ground beneath is littered with fallen nuts! Here are some tips for identifying using leaves and bark as well.
Black walnut trees have compound leaves that are made up of ovate-oblong to ovate-lanceolate leaflets with serrated edges and pointy tips. The leaflets are arranged alternately along a shared stem, though sometimes you have to look closely, since they can appear to be almost opposite from each other. The leaves also carry some of the same distinctive citrusy-antiseptic scent the nut does.
Black walnut bark is dark grayish brown with deep furrowing and ridges. The heartwood is a rich dark brown, and prized for furniture making and other woodcraft.
Black walnut trees produce an abundance of round nuts.
The green hulls are rough and somewhat resemble an under-ripe orange. They have a distinct smell; it’s a strong earthy, medicinal smell, with a citrus overtone. The hulls turn brown/black when left on the ground, or when damaged, so many of the green hulls may have brown/black spots and cracks, especially if the tree is very tall, and the nut is falling from a great height.
The inside of the green hulls are spongy, fibrous, and yellowish in color, which darkens quickly with exposure to the air. The inside of the black hulls- or just underneath the black spots on your nut hulls- are often a pitch-black, inky mess, usually with some number of little worms squirming around. Don’t worry, this doesn’t mean your nut is bad! Those worms are just in the hull, not eating on the nut itself.
In both of these types of hulls, there’s a single nut. Without cleaning, this will have a pretty good amount of the pulpy insides of the hull still attached. Once cleaned, it will be revealed that you have a brown nut- sometimes with some black staining- striped with deep ridges. Little green patches may appear on the nut as it dries.
Cracking the nut itself open (which is no easy task!) reveals a heart-shaped cavity. You can see this in the picture above. The nutmeat inside is white in color, with a papery brown husk.
When to Harvest Black Walnuts
When fall begins to approach, and you can hear the nuts start to fall from their trees, go out in the woods and start looking for black walnuts! You’re looking for mostly green nuts, so leave any that are completely inky black where they lay. A few black spots or cracks aren’t bad, but leave the super-soft ones, the ones that ooze a black, inky liquid when you squeeze them.
To check whether your black walnuts are ready, press your thumb into the hull- if your nuts are part green, part black, press into the green part. Your thumb should easily be able to make a visible dent in the hull. If the hull is super hard and doesn’t give at all under your finger, it’s likely under ripe.
Be prepared to process the same day, or within two to three days, in order to avoid the nut hulls turning black and liquifying. This can adversely affect the flavor of the nut, if the liquid of the decomposing hull seeps through the shell and gets through to the meat. Plus, you need to get those hulls off to start curing your walnuts!
Techniques to Remove the Hulls
Before drying and curing walnuts, the hull should first be removed. Otherwise, the flavor of the nut can turn strong and bitter.
Black walnuts stain everything. These juicy hulls have a powerful dye lurking under the surface, which you can see better in the more decomposed hulls- that black, inky liquid. However, even the totally green hulls, with their clear juices that go spurting out at a strike, will stain. That clear juice will darken into brown wherever it touches.
It’s a good idea to wear rubber gloves and old clothing when processing black walnuts.
If processing a few nuts…
Using a hammer, rock, or a brick, smash the hulls of the black walnuts to break them up a bit. Peel off the hull with gloved hands, and collect the nuts in a container.
For a larger amount of nuts…
We spread the nuts out on a tarp and use a digging bar to smash them- take care not to hit them too heavily, or you might shatter the nut inside!
Another way to break up the hulls, if you don’t have a digging bar, is to stomp on them. Some people claim that you can drive over the nuts with a vehicle to smash the hulls, though we cannot verify this, as we’ve not tried it.
No matter how you choose to smash the hulls, pick through them afterwards with gloved hands to retrieve the nuts, prying off the hulls and tossing the nuts into buckets for cleaning.
Save Some of the Green Hulls!
If you’re making tincture (recipe below) or salve (recipe on our sister site, The Nerdy Farm Wife), gather up some of these green hulls, break them into smaller pieces, and collect them in a jar to infuse in alcohol or oil. Process them as soon as possible, ideally within the same day as collecting.
Collect green parts of the hulls that haven’t turned black or mushy, and avoid any with worms since we don’t want to use those in our tincture and salves.
Washing the Walnuts
Now that the hull has been removed, it’s time to wash the nuts! We want to get rid of that goopy extra pulp so it can’t break down and get bad-tasting liquid in the nut, and also so we can float-test them for good nuts!
Some people wash their nuts with a garden hose, but that didn’t get them clean enough for our tastes. Other people use a power washer. Here’s how we wash our black walnuts:
Fill a bucket about 1/2 full with nuts, and add enough water to cover. Using a corded drill with a large paint stirrer attachment, spin the bucket of nuts for 3 minutes. The water will turn inky black, and the nuts will strike and bounce against each other. After time is up, pour out the bucket over a screen, and rinse with a water hose.
This leaves the nuts clean and easy to handle for the next step- float testing!
A note on Juglone:
Black walnut trees release juglone, a chemical that suppresses growth of some plants found beneath the range of their canopy. Juglone breaks down relatively quickly when exposed to air, water, and decaying bacteria, but as it is present in not only the roots of the black walnut tree, but also the leaves and hulls, caution should be taken not to let the hulls or the water pour-off from cleaning the nuts reach favorite plants.
There is a good number of plants tolerant to the effects of juglone, among them the sugar maple tree and ginseng. There are also many plants sensitive to juglone exposure. It’s best to err on the side of caution, and dump the hulls away from your garden. Actually, if you have chickens, you can give them quite the treat by letting them have a go at the hulls- they love the worms that hide inside!
The Float Test
Float testing your nuts is an easy way to tell good nuts from bad- all you need is a bucket of water, and a pile of cleaned nuts!
Place a handful of nuts in a bucket of water. Any that float are bad: discard them. Give the bucket a good stir, making sure to do so vigorously enough to disturb the nuts, and check again for floaters once they settle. If they’ve all sunk to the bottom, and none are floating, that means they’re full, good nuts, and you can remove them from the bucket to a different rack to begin drying.
You can crack open some of those floaters to see inside, if you’d like: the reason they float is because there’s an air pocket, inside the nut, which can mean that inside, there could be anything from an incompletely filled nut, to an underripe nut, to a shriveled-up nut, or simply a completely empty nut.
Curing and Drying
Alright, your nuts are clean! Now that you’re done there, it’s time to let them cure and dry.
Spread out the wet, fresh-washed nuts on a screen or place with good air circulation, preferably in the sun, until the moisture is all gone. Stir the nuts once or twice to make sure all the sides get dry.
Once dried, spread the nuts out to keep curing and drying in suitable containers: some people use milk crates. We have a set of screened nut boxes we use that work beautifully. However you do it, watch out for the squirrels! Unprotected nuts will often be stolen right out from under your nose, and even if you protect your nuts, you might find that the squirrels will try and pull off a heist anyway- putting some form of top that still allows air circulation, but is too heavy for a squirrel to move, might be a good idea.
Now that your nuts are spread out, dry, and protected, all that’s left to do is wait! The nuts need to cure for 2-3 weeks before using, so leave them somewhere with good air circulation that’s protected from moisture, and stir them around once a day or so, if you happen to think about it.
Why do I need to cure my nuts?
Curing helps dry down the nut meat inside the nut- which is a good thing that we want! Fresh nuts have a tendency to cling stubbornly to the walls of the shell, and are rather watery in flavor. Curing not only makes it easier to harvest the nuts, but improves and condenses the flavor of the nutmeats!
Once they’re finished curing, they’re ready to crack!
Cracking & Storing Black Walnuts
Black walnuts are too tough to be cracked with any old normal nutcracker! Try using a hammer, back of a hatchet, or heavy rock to crack them open, then use a nutpick to remove the nutmeat inside.
Odds are, you’re not going to get full halves your walnuts, but instead lots of pieces. Don’t worry, they’ll still taste perfectly fine!
Once the nutmeat is removed from the shell, collect them up into a container, label with the date, and freeze. Freezing is the best way to get the longest period of use out of your shelled black walnuts, and will help keep the looming specter of rancidity- the end point of all uneaten nuts- at bay.
From here, use them as you see fit! Eat them plain, roast them, toss a handful into your banana bread, into muffins, candy them… However you so desire to use them, enjoy your foraged feast!
Uses for the Hulls & Leaves
Black walnuts aren’t just for food! The leaves and hulls contain compounds that are useful for natural home remedy purposes too!
Black Walnut Oil & Salve
Use the green hulls to create an easy but effective salve that may be helpful for athlete’s foot, toenail infections, psoriasis, ringworm, and other skin ailments.
You can find our Black Walnut Salve Recipe at our sister site, The Nerdy Farm Wife.
How to Make Black Walnut Hull Tincture
Black Walnut Tincture is used externally to spot treat warts, psoriasis, impetigo, or fungal infection/rashes. It’s also considered a natural source of iodine, so some apply it daily to their skin for potential thyroid benefits.
Others use the tincture internally for parasites, especially helpful if traveling to an area with bad water. In his book, The Earthwise Herbal, Volume II, herbalist Michael Moore recommends a low dose of 1 to 3 drops, 1 to 3 times per day. Don’t take for extended times or if pregnant.
To make: Fill jar 1/2 way with broken up or chopped pieces of green black walnut hulls (avoid mushy blackened parts with worms), fill jar with 40 to 50% (80 to 100 proof) vodka. Infuse for 4 to 6 weeks, strain. Label and store in a cool dark spot for 1 to 2 years.
Black Walnut Leaf Infusion
If hulls aren’t available, or you need something fast, try using the leaf instead. Use walnut leaf infusion similar to a wound wash or dilute iodine wash. It can also be used on irritated or inflamed areas.
To make: Place 1/4 cup chopped fresh leaves in a small saucepan. Cover with 3/4 cup water, bring to boil, cover, reduce heat, and simmer for 10 minutes. Remove from heat and cool, while still covered, for 5 minutes. Makes about 4 ounces of infusion. Freeze in ice trays for future use (1 oz per cube = 4 cubes).
Fresh Leaf Poultice
Walnut leaves can be used to create a poultice while you’re out and about hiking. Simply mash or chew up some leaves and apply to bug bites, scrapes, or to stop minor bleeding. We’ve also successfully eased a sore tooth with a leaf poultice placed right beside the offending tooth.
Our articles are for information and idea-sharing only. While we aim for 100% accuracy, it is solely up to the reader to provide proper identification. Be sure to seek out local foraging classes and plant walks, and invest in mushroom and foraging guides suitable for the area you live in, since some wild foods are poisonous, or may have adverse effect.