Black Walnut Trees

Facts About the Infamous Black Walnut Tree

By George and Becky Lohmiller
August 19, 2020
black-walnut-trees-roots-evil-ascending-the-giants-wikimedia-commons
Photo by Ascending the Giants: Wikimedia Commons

The black walnut tree (Juglans nigra) is one of North America’s most valuable and beautiful native trees, but it does have a “dark side.”  Here’s what you should know before planting a black walnut in your yard—and how to harvest and eat the tasty walnuts, too!

Facts About the Black Walnut Tree

  • The easily worked, close-grained wood of the black walnut has long been prized by furniture- and cabinetmakers for its attractive color and exceptional durability. Its logs are in such demand for veneer that “walnut rustlers” have made off with trees in the dead of night and even used helicopters in their operations. 

  • The early settlers discovered black walnuts growing in mixed forests from Canada to northern Florida and west to the Great Plains. They found that its rich-brown heartwood was exceptionally resistant to decay and put it to use as fence posts, poles, shingles, and sills.

  • When surrounded by other trees in the forest, black walnuts grow straight and tall with few, if any, lower branches.

  • When planted in the open, the tree will branch out closer to the ground, developing a spreading shape that makes it easier to harvest its sweet, round, two- to three-inch nuts.

  • Settlers snacked on the nutritious walnuts out of hand, added them to soups and stews, and ground them into meal for baking; the hard shells provided a perfect package for storing the nuts over winter.

Black walnut tree

The “Dark Side” of Black Walnuts

Although the black walnut has many uses and benefits, the tree does come with a caveat: the black walnut’s roots, which may extend 50 feet or more from the trunk, exude a natural herbicide known as juglone. This substance is also found in the tree’s leaves and fruit husks.

Juglone does serve a purpose, though. It inhibits many plants’ growth under and around the tree, thereby limiting the tree’s competition, leaving more water and nutrients for itself. 

Tomatoes, potatoes, apples, pears, berries, and some landscape plants such as rhododendrons, azaleas, and lilacs may be killed or stunted if grown in close proximity to black walnut roots or within the tree’s drip line (i.e., under the tree’s canopy). Plan your landscaping accordingly!

A Great Shade Tree

In spite of this, black walnuts make great shade trees for larger properties. They commonly grow to 50 feet or taller and about as wide, but specimens of more than 100 feet have been recorded.

Black walnut’s large, fernlike foliage provides light, airy shade for those grasses and ground covers not affected by juglone. In autumn, the leaves turn bright yellow, contrasting nicely with the tree’s rugged, dark bark.

Black walnuts require a deep, fertile soil with a near-neutral or slightly acidic pH. They are pretty much disease-free and are threatened by few pests.

Picking Up the Nuts

Thud! Thud! Most walnut tree owners have a love/hate relationship because of the fruit which the tree drops in late summer though October. The size of a baseball and colored lime green, the fruit is quite heavy. It makes quite a mess and can be viewed as a nuisance.

Walnut tree owners will spend hours picking up the fruit some years. If you don’t remove the nuts, you’ll trip over them in the dark for the rest of the year (while they rot and mold on your lawn). Hire the kid down the street to pick up those the dropped walnuts (just be careful not to pay per nut—you’ll go broke)! 

black-walnut-shutterstock_182861756_full_width.jpg
Photo Credit: John A. Anderson

Harvesting and Eating Black Walnuts

If you’re willing to do the work of cracking the outer shell, the “meat” inside is edible, as the squirrels will attest; squirrels have little problem chewing through the shells. (Note: Black Walnuts are different than the English Walnuts more commonly sold in stores and shown in the photo above.) 

The sweet, earthy nutmeat inside is well worth the effort. Your grandparents may have harvested the walnuts which can be eaten raw or added to baking (cookies and bars). They can also be toppings on ice cream and cakes, enjoyed as a sweetened candy nut, or ground into meal for a unique flour. 

To harvest, collect the nuts as soon as possible to avoid mold and remove the husks immediately. Wear gloves as the husks stain your hands (and anything they touch). If the nut is too hard, wait a few days and it will brown and soften up.) To remove the husk, you can simply step on them gently with an old pair of shoes. Hose down the nuts in a large bucket to remove any remaining husk.

Dry the walnuts for a couple of weeks on a screen or drying rack or in a hanging mesh bag. You can store them unshelled up to a year. Crack the shell with a hammer to get to the nut meat. (Strike at a 90-degree angle to the seam until the nut cracks). Use pliers to easily clip away the shell to release the nutmeat. Allow the freshly removed nutmeat to dry for a day before storing.

Do you have a black walnut tree? Please share your comments, questions, and advice!

Source: 

This article was originally published in March 2008 and has been updated.

2021_gardening_calendar_ad_updated.png

Reader Comments

Leave a Comment

Nothing but grief

I purchased a property on a small lot with a mature black walnut--at least forty years old, maybe more--in its small front yard. This thing kills everything that I and my neighbors try to grow in our front gardens, even plants rated tolerant of juglone. Because of tree-friendly local regulations, I'm not allowed to remove the tree, and even if I could it would take years for the poison to dissipate. During nutting season I'm picking them up constantly to protect myself and neighbors from tripping and the local dogs from getting sick trying to eat or play with them.

I've tried processing the nuts myself by hand several times and just gave up--between all the staining goop and the trickiness of opening those tough shells without smashing the insides, it's really a job better suited to machines.

To top it all off, it's an ugly tree--much too big for the space it's in, has to be cut back into a deformed shape so it's not hanging over the roof. It's the last tree to grow leaves in spring and the first to drop them in fall. I've never seen an animal nesting in it.

I suspect that some people on here with fond memories of their black walnut trees are actually thinking of English walnuts.

Black Walnuts

Black Walnuts are toxic to dogs.

Memories of my Grandfather

When I was little my Grandfather collected a large number of black walnuts from a tree in our town. He carefully laid them out on the basement floor to dry out. I remember the floor getting stained, my Dad freaking out and walnuts ending up in just about everything we ate for months! Oh the memories from “back in the day”.

need help

My walnut tree has not had nuts for 2 years. What can I do for it?

walnut trees producing nuts

The Editors's picture

Hi Irma, Usually, walnut trees alternate years of nut-bearing.  But also it depends how old your walnut tree is. At age 20, they’re barely out of their juvenile years!  And finally, if you have a lot of squirrels, they may be stripping the tree early. Hope this helps.

black walnuts

I planted 5 black walnuts in a marshy area I do not use in one of my fields then I forgot about them, this was at least 15 yrs. ago. Two years ago I was removing dead wood in the area and discovered 3 had survived and one was covered in walnuts. Just a very pretty tree and a lovely surprise harvest.

No food is "safe"

Depends on food. My guidelines: soda is always safe, various bars and jerky are good unless they're mouldy, canned goods over 50% are safe, meat over 80%, and sardines over 95%. Seriously, sardines are a trap. Not sure how accurate that is, but I haven't had food poisoning for more than a year in game.

growing from seed

I have collected over 400 walnut seeds and set them out in the sun to dry. When the skin gets black, remove it to expose the nut. I then rub a root hormone on them and put in a garden / potting soil and winter them over winter in a cold basement.

In the spring place them in the sun and moisten (not drown) and repeat when the soil gets dry. Let them alone and they will sprout. The ratio was about 20 trees (plenty) of the 400. Transplant to a larger container and let them grow and harden off.

When they get about 4 inches high transplant to a garden area remote from eatable plants. Then when developing transplant to a final resting place or give to neighbors and friends if wanted.. Been doing this many years with good results I figure. Could also sell to a nursery. Takes time.

The walnut tree is in the family as the Butternut. Grow them the same way. Many of these trees are disappearing. Hey, give it a shot, nothing to lose. I did this in southern Vermont with long dark winters.

The black skin is certainly staining.There are many places on line with related info and some places sell the internal seed in bulk. Machines de-shell. You can buy the nuts on their web sites. (maybe plant the seeds???).

dying walnut tree

I have seen black walnut trees growing close to a house in a place that subsequently was planted to a lawn. The excessive fertilization and watering of the lawn resulted in a root fungus that killed a very nice large native black walnut. beware of over-watering the lawn. Fwiw.

I think my tree is dying.

I think my walnut tree is dying. A small section as fallen off with just a touch. It's at least 110 years old. What should I do?

Black walnut fruit rot

If the walnut fruit husk has begun to rot on the ground is it too late to harvest? Basically, can you just let the walnut husk rot away and still keep the nut or will it rot too?

Walnut Husks

The Editors's picture

It really depends on how far gone the husk is. If the husk is completely rotted, we wouldn’t recommend keeping that nut, as the nut will have been left exposed to fungi and pests that could have penetrated the shell. However, if the husk looks like it’s only just started to break apart, you can get away with collecting the nut. 

Black walnut cleaning

I use a small cement mixer,run for about 20 min for each batch of 5 gallon, wtth water

Black walnut

If you don't clear the fruit from your yard, or if you leave a small pile in a corner, you will be "blessed" with a completely bare patch of soil for a year. Ask me how I know.... The last time the wind blows as many walnuts seem to fall as have fallen all summer and fall together.

Black walnut trees

Are there people that buy very old black walnut trees? I have 3 very old trees in my yard and was thinking of getting rid of some.

Colic in horses

I have also been told that black walnuts are toxic to horses and can cause severe colic. Black walnuts should never be on a property where horses are kept.

Black walnut trees and horses

The Editors's picture

Yes, indeed. There is a similar comment lower on this page. Horses are generally only affected by shavings made from the tree. Do NOT use in bedding. 

Squirrels

I have a black walnut tree in my backyard. Its super beautiful and provides a nice shady cover for the hot Mid-Atlantic summers. The biggest problems is that it attracts squirrels (aka tree demons). They not only steal all my tomatoes, dig holes everywhere, but they also have been chewing my outdoor lights and stealing the bulbs. They are cute buggers but what I pain - I never knew they were such a nuisance.

Giant Black Walnut trees

I have read that before contemporary road paving, that many early 1800s rods were paved with black walnut slats. The wood was plentiful, inexpensive, tends to resist rot and last longer in the damp earth than other wood. It was an effective way to maintain roads in mud seasons. In earlier times there were giant black walnut trees, 30' in circumference and more than 200' tall. These were all cut to pave roads.

Black Walnut Tree

I let the squirrels have them. I honestly didn't know they were edible for humans. My tree is right by my driveway which makes a pretty big mess.

Black Walnuts

I love in south Louisiana and remember as a younger adult always having a few trees. Well, time has passed and the trees are gone. I with I could find someone that would be willing to send me some.

Black walnut tree

Wonderful tree but I am told it can cause colic in horses? Is this accurate?

Black walnut toxicity

The Editors's picture

Black walnut trees are odd in that they are safe for all livestock except horses, and horses are generally only affected by shavings made from the tree. Do NOT use in bedding. Black walnut trees are, however, toxic to some species of plants if growing within a certain range of the tree. In fewer instances, shedding pollen can cause allergic reactions in horses and people as well as kidney effects in animals that ingest hulls.  Black walnuts do not pose any threat of toxicity to humans but they are toxic to some species of plants if growing within a certain range of the tree so consider this if you are a gardener or homeowner.

Black Walnut Tree

I actually have a question. What would make very Mature trees not produce nuts? We have about a dozen and for some reason this year some trees have none.

TAP THEM FOR SYRUP

I tapped three of my walnut trees for sap to make syrup last spring for the first time. The syrup is like maple, but with a butterscotchy overtone. Delicious. I plan to buy more taps and tap more trees next spring. They do not yield as much as maple trees, but since I have no maples but plenty of walnuts, I'll happily make due with what I have. Squirrels bury the nuts, starting many new trees each year. Just cut down the ones you don't want to grow before they get too big. You may have to cut them down a few times before they stop coming back.

This article mentioned that tomatoes don't do well under walnut trees, but I read elsewhere that they are juglone tolerant. So I have a few tomato plants within the drip line of some maybe 15 year old trees. "Mrs. Maxwell's" variety is doing the best so far, "Delicious" not so good, and "Amish Paste" somewhere in between. A hot pepper plant is also doing well, as are two elderberry bushes I just got this year.

black walnut trees

I have been enjoying the comments about black walnut trees. We have a lot of them here in central Pennsylvania and all the comments, pro and con, are true! They are messy, dangerous and delicious! I am continually pulling baby walnut trees out of my garden beds because the squirrels seem to think it's a good place to 'plant' them. I've watched them do it. They will then put a nice leaf over the spot and pat it down. I have to say that I love squirrels...but am not too happy about walnut trees coming up in my garden.

Poisonous to horses

Be aware that if you live in a rural area, that Black Walnut is highly toxic to horses. Even if shavings get in their stall, it can kill them.

Black Walnut Trees

Besides collecting the walnuts, we also tap our black walnut trees to make syrup. It has a more nuanced flavor than sugar maple syrup and is one more way to utilize our trees.

Black Walnut Trees

We have 4 Black Walnut Trees in our yard. We do love / hate them! The nuts are ankle breakers if not collected. I have a "walnut wizard" which makes picking them up SO easy! I couldn't co-exist without it! The hulls are dangerous. My hubby blasted them all off with a pressure washer one year and the next day he was covered in acid burns. He had to seek medical care and was on allergy meds & burn cream for a week. His Dr. said he had never seen anything like it! BEWARE THE HULLS!!!

Black Walnuts

I grew up on a farm in Virginia with a black walnut tree in the front yard. We would gather the green nuts and pile them under the tree. When the hulls turned black, we would put them in the driveway and my father would run over them with his truck to break the hulls off. Then we would spread them out to dry and crack them open with a hammer on a good hard rock. Yes we went to school with stained hands but so did other kids. We all knew this was stain and not dirt, so no one cared. They also knew it was because we were doing our part to help the family. Those were good memories!

Pages