Do you have black walnut trees nearby? See how to take advantage of this foraged food by learning when to harvest and how to hull, cure, and store black walnuts.
In our area, black walnuts begin to mature and fall from the branches in late September into October. We try to gather as many as we can daily before the squirrels and chipmunks snag them all to hide away in their winter storage. Trust me, there is usually plenty for all of us.
The eastern American black walnut (Juglans nigra) is a native tree found throughout the eastern parts of the US and Canada. It also adapts well when planted in non-native areas up to USDA zone 4.
Many old farmsteads had at least one or two black walnut trees on the property. Black walnuts trees were highly valued as a food source, shade tree, and wood used for fine carpentry work. The hulls of black walnuts were used to make ink, medicine, and as a dye for hides and fiber.
If you don’t have a black walnut tree in your neighborhood, ask around and you may find someone who would be happy to have you pick up the hard nuts from their yard.
Although foraged black walnuts are free, there is a lot of time and labor involved with shelling, cleaning, curing, and cracking the nuts. It is worth the effort when you taste them though. Black walnuts have a much bolder walnut flavor than the ones you purchase in the store. So you can use less in your favorite baked goods.
It’s important to note, black walnut trees produce a substance that is toxic to other plants that helps the tree keep other vegetation from competing for valuable nutrients and moisture. The roots, leaves, and nut husks contain a natural herbicide called juglone that inhibits the growth of some plants. Do not add hulls, shells, or rinsing water to your compost or dispose in an area that may harm plants or garden soil.
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How to Harvest Black Walnuts
It is easy to tell when black walnuts are ready to harvest. Just watch the tree for signs.
The leaves of the tree will begin to show its fall colors, turning from green to yellow. Then the fruit will fall from the tree when ripe. The ground beneath the tree will be littered with what looks like small green tennis balls.
We like to take advantage of the foraged walnuts whenever we can and scoop up the fallen nuts from the ground.
Grab walnuts that are still mostly green to brown. Avoid black, moldy, or rotten nuts that look like they have been on the ground for a while. These will probably be infested with insects and fungus. Also, the longer the husk remains on the walnut after falling from the tree, the bitterer the nut can be because it absorbs the tannins from the fleshy husk.
Gather the black walnuts into buckets. You may want to wear gloves as you gather because sometimes there is rotting, bugs, and possible staining. Be mindful of your footing. It is easy for the nuts to hide among leaves and other debris on the ground. Also, watch for falling nuts when under the limbs of the tree. It wouldn’t be crazy to pop on a bike helmet if you happen to have one.
Curing Black Walnuts
Harvesting the black walnuts is the easiest step. Once the fruit is harvested, you will need to remove the husk, wash the walnuts, and let them cure for several weeks before storing or cracking.
Remove the outer husk from the walnut
A fleshy outer hull protects the walnut inside. The hull starts out as green, and then turns dark brown as it ages. Inside the husk, is the walnut encased in its shell. Inside the shell is the prize, the nutmeat.
The hull must be removed before curing the walnuts. Try to remove the hull and clean the flesh from the walnut within a few days of harvesting. If the hull is left on, the juices can penetrate the walnut shell and turn the nut bitter. The hull is also easier to remove when it is still soft and fleshy. If you discover the husks are dried on to your walnuts, soak in water overnight to soften them up.
Removing the outer hull is a messy job. This skin will stain everything it comes in contact with. Wear old clothing and several layers of gloves when working with black walnuts. You’ll need to experiment with ways to get the husk off to find a method that works well for you.
Smashing them with a hammer on a hard surface will crack the hull and make it easier to peel off the rest of the husk. After breaking the skin, roll the fruit on a firm surface until the majority of the husk loosens. Then peel off as much as you can with your gloved hands.
You can also try hitting the fruit with a hammer and nail to break through the flesh, and then tear it off with your hands. Be careful if you are using a knife. Once the skin is pierced, it becomes very slippery, and it will be really easy to cut yourself.
As you remove the husks, a brownish-yellow liquid will bleed out and stain everything it touches. It can even seep through gloves. It won’t wash off your skin, but will fade over a week or two.
Don’t panic if you see worms or maggots in the flesh of the hull. There are often worms inside the husks that are larvae of the husk fly. It is totally gross, but the larvae won’t penetrate the shell of the black walnut.
Wash the Walnuts
Once the husk is removed from the walnuts, scrape off as much of the fibrous flesh as you can from the nut, and then drop them into a bucket.
Use a hose with a spray nozzle and high-pressure spray the nuts in the bucket. Stirring the nuts with a stick will help them rub together and break loose the remaining juice and debris.
Repeat rinsing a few times, and even consider scrubbing the nuts with a brush to remove as much of the husk material as you can.
Be careful with splashing water because it will stain. Remember that the black walnut also produces a substance that is toxic to other plants. Be mindful where you dispose walnut husks, seeds, and even the rinse water so you don’t kill other plants or contaminate the soil.
Remove and dispose any nuts that float. These contain malformed or immature walnuts that won’t be any good.
Cure the Black Walnuts
After the black walnuts are hulled and rinsed, they need to cure for a few weeks before storing and cracking. The curing process helps the flavor of the nut develop, and makes cracking the shell much easier.
Spread the black walnuts out in a single layer and let the nuts cure in a cool, dry area, out of sunlight, for two to three weeks. Be sure to cure the nuts in an area where squirrels, chipmunks, or other rodents can’t find them, or you will be left very disappointed.
Storing Black Walnuts
After several weeks of curing, give the walnuts a shake. If the walnuts are finished drying, you will hear it rattling slightly in the shell. Crack a walnut to test it. The kernel should be firm and snap easily.
Storing black walnuts in the shell: Once the walnuts are cured, they can be stored unshelled in a cool, dry place. Store in mesh bags or baskets for up to a year.
Crack and shell the black walnuts as needed for recipes. You’ll need to crack about two pounds for about one cup of walnut meat.
Storing black walnut meat: Black walnuts have a high oil content that can cause them to spoil at room temperature. Once the walnuts are cracked, store the nutmeat in an airtight container in the refrigerator or freezer.
Black walnut meat will stay fresh in the refrigerator for about six months. Frozen walnuts will last about a year. The texture changes when frozen so they are best used in baked goods.
Tips for Cracking Black Walnuts
Black walnuts are much more difficult to crack than the regular walnuts you buy in the store. I found it impossible to get whole walnut halves from black walnuts. The inside of a black walnut contains several chambers and the nutmeat itself is embedded into these spaces.
You will need to crack and remove individual pieces of nutmeat with a nut picker. A pair of wire cutting pliers can come in handy for clipping the cracked shells to release the nutmeat. Be sure to sort through the black walnut meat very carefully and remove all shells.
Tip 1: Plan ahead
Cracking black walnuts takes time and a lot of patience. Review your recipes ahead of time and plan on shelling the nuts before starting the recipe. Store freshly extracted nutmeat in the refrigerator until you are ready to use.
Tip 2: Experiment with ways to crack black walnuts
Although shelling black walnuts can be challenging, the rewards are delicious. Try experimenting with different methods until you find an efficient process that works for you:
Hammer on a hard surface: Hold the black walnut on a concrete surface pointy end down. Strike the walnut firmly on the top with a hammer hard enough to crack the shell.
The walnut should crack in half. Repeat the process on each half. Place the thick side of the walnut half on the concrete and hammer gently on the top edge. The nut will crack into rough quarters.
Use a bench vice: If you have a bench vice in your workshop or garage, put it to work cracking walnuts. Place a shallow container beneath the vice to catch walnut pieces and shells. Position the black walnut in the vice lengthwise. Slowly increase the pressure until the walnut shell breaks. Usually, the walnut will crack along the seam. Repeat the process with each half.
Use a black walnut cracker: A black walnut cracker is expensive, but worth it if you process a lot of black walnuts each year because it will save you lots of time and effort.
Try vice grip pliers: Adjust the width of the vice grip jaws to be just slightly smaller than the walnut. Place the jaws along the seam of the nut and clamp down until the walnut cracks.
Smash the walnut with a brick or rock: Position the black walnut against a hard surface and hit it with a rock.
Black Walnut Research and Further Reading:
- Black Walnut Toxicity to Plants, Humans and Horses – Richard C. Funt, Jane Martin
- Preserving Fresh Walnuts to Maintain Nutritional Content – Diane Rellinger, Michigan State University Extension
- Using Black Walnuts – Jane Hart, Michigan State University Extension
How to Harvest and Preserve Black Walnuts
- 1 dozen black walnuts
- Gather black walnuts from beneath the trees. Grab walnuts that are still mostly green to brown. Avoid black, moldy, or rotten nuts that look like they have been on the ground for a while.
- Remove the outer husk. Wear old clothing and gloves to protect from staining. Smash the walnuts to break the skin, and peel off as much of the husk as you can.
- Wash the hulled black walnuts in clean water. Scrub with a brush to remove the remaining husk and juice. Discard walnuts that float.
- Spread the washed black walnuts out in a single layer, and let the nuts cure in a cool, dry area, out of sunlight, for at least two or three weeks.
- Test the black walnuts to check if they are finished curing. Shake the nuts. You should hear the nut rattling in its shell. Crack one and taste it. If the shells are brittle and the nutmeat firm, they are cured.
- Store the cured black walnuts in their shell in mesh bags or baskets in a cool, dry place for up to a year. Shell the black walnuts as needed for recipes.
- Once the walnuts are cracked, store the nutmeat in an airtight container in the refrigerator for six months, or freezer for up to a year.
- You'll need to crack about two pounds of black walnuts in the shell to yield about one cup of walnut meat.