Black Walnut Trees: Roots of Evil?

George and Becky Lohmiller
Photo by Ascending the Giants: Wikimedia Commons

The black walnut tree is one of our most valuable and beautiful native trees, but it does have a “dark side,” too. (Humor required.)

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.

A Brief History of Black Walnut Trees

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 walnut grows 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.

The settlers snacked on the nutritious nuts 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.

The “Dark Side” of Black Walnuts

Unfortunately, the black walnut’s roots, which may extend 50 feet or more from the trunk, do exude a natural herbicide known as juglone that prevents many plants from growing within their reach. 

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.

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, and 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, with the exception of perhaps an occasional helicopter.

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


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

Reader Comments

Leave a Comment

Walnut keep on giving

As a novice woodworker, the black walnut wood is beautiful. I am always looking for walnut trees that have served their useful life and now can be put to further beautiful use. Connect with me if you need to get rid of one near Dayton OH.

Roots of Black Walnut Tree lifting up concrete path

Our tract home was built in 1965 on land that was a walnut orchard. We have a very old Walnut tree in our front yard. It has lifted our walkway which is less than 2 ft. from the trunk. I would like to to build a new walkway approx. 16 ft. from the trunk. There are horizontal roots in that area. Can I cut those roots to allow for a walkway since it's 16 ft. from the trunk? FYI..the tree has 3 trunks that grew from the cut off center trunk before I purchased the home.

Black Walnut Roots

Hi Jan,

Yes, it would be safe to cut some of those roots without affecting the tree. Most tree roots go deep underground, leaving it plenty of routes to get water. 

The husk seems larger than last yr. around the nut this year (

does this mean the weather this winter is going to be cooler ??

walnut weather??

There is an adage that suggests a large crop of walnuts indicates a cold and snowy winter but we do not know of a proverb about the husk. Keep watch this winter and maybe you’ll see a relationship…and you can “invent” a proverb to fit the conditions!

Be careful where you plant

A previous owner planted a black walnut tree in front of my place decades ago. It's not particularly attractive, way too big for the space it's occupying, and during the years when it produces nuts (which to my relief isn't every year) there are a couple of months where you literally can't walk past my house without tripping on the things. I try to keep them picked up because I don't want anyone hurting themselves or for a dog to bite into one (the paste that coats the nut between the outer and inner shells is highly toxic) but as soon as you've collected one bushel basket full, down comes another. Add to this the fact that these trees can last for literally hundreds of years, grow to enormous size, and cutting them back only makes them produce MORE nuts, and you've got a monster on your hands.

Trimming Black Walnut

We are in MN. Is there a certain time of year that black walnut trees should be trimmed, whether the branch is dead or alive?
Thank you.

Pruning black walnut trees

Prune during the dormant season. Do not apply paint or other sealants to pruning cuts. Wait until walnut trees are 3 to 4 inches in diameter. Trees up to 10 inches in diameter may benefit from pruning. 

Do not remove more than 25% of the live crown in a single pruning or prune higher than 50 percent of total tree height. (The “crown” of a tree refers to the branches extending from the trunk or main stems. The “live crown” refers to the part of the crown that has live foliage.)

Prune only branches less than 2 inches in diameter, preferably less than 1 inch. Larger pruning cuts heal slowly and may lead to decay and ring shake. Prune up to 9 feet high; if possible, prune timber trees up to 17 feet in two or more pruning operations. Stem forks, crooks, or large branches may restrict pruning height.

apples trees

I have a 25 ft black walnut tree I've grown from a nut brought from Ontario to Vancouver Island.
There is an apple tree growing within 10 ft of the tree. Will te roots of the walnut kill my apple tree and will they affect the fruit in any way.

apple and black walnut

The only “apple” trees that we can find in our information/sources that tolerates the juglone (the chemical in black walnut tree buds, nut hulls, and roots) are crabapple and mayapple. We checked several, so we would say no, the apple will not survive. Our sources suggests that the highest concentration of juglone is under the canopy but toxicity symptoms can appear on plants that are, on average, 50 to 60 feel from the tree trunk.

BTW, we are in awe of the fact that you grew your 25-foot black walnut from “seed”!

Nuts on the ground, the fall harvest

I have about 8 walnut trees on my property, with one being in a clearing. I have noticed these little white worms, quickly invading the green outer shell of the nut on this one particular tree within days of being on the ground. what are these little buggers?

black walnuts

The Black Walnuts are very large this year but many the nut isn't ripe it's dried out - what would cause this ?

Black Walnuts are also anti-parasitic!

They are at least anti-parasitic, for raccoons. (although I have seen black walnut powder listed as an ingredient in various nutritional supplements to detoxify or de-worm humans, too)... Anyway, after discovering a litter of abandoned baby raccoons, I sought out my local nature center, to take them in, and help them out. I was turned away, because they didn't take such animals, but they gave me the phone number of a certified wildlife rehabber, who did. This person was overwhelmed with the critters, so she took them with the condition that I was willing for her to teach me how to do it, and officially sub contract me, and have me do it, myself. This is how I learned that black walnuts are a favorite food of raccoons. Not only is it nutritious, but the walnuts provide a natural anti-parasite property, that helps to prevent or relieve intestinal worm infections. On a side note, let it be known that raccoons do not prefer to eat garbage, and are actually very selective about what they eat, but unfortunately, they don't always have enough areas for foraging for such foods. They actually eat a diet very similar to bears... Just on a smaller scale. I live in the country, where they have plenty to eat, and they've never gotten in my garbage. But similarly, to bears, I suppose some of them get into the habit, out of convenience. Sorry for going off topic, but perhaps this will explain why wild animals are attracted to these trees, on people's yards.

Black Walnut Tree Watcher

Not someone who knows much about trees, I was surprised to find out the trees that line my country road, where I wait for my kids at the bus stop, are actually walnut trees. I actually thought they were dropping some kind of apple-like fruit. There is a group of 7 crows that live in one of them, and I have enjoyed watching them eat the walnuts (as I now know them to be), by knocking them off the branches, and then centering them in the dirt road, along the tire ruts, for cars to run over them and crack them open. Crows are smart! It makes even more sense, realizing these are not apple-like fruit, but actually nuts. The walnut trees line a pasture for cattle and corn, alternately. They are very, very tall old trees. And indeed, they do provide a lot of shade. One of them has the remnants of a fort, built into it... a fort that must have been built some time ago... now that fort is at least 15 feet from the ground. Thank you for posting this article so I could learn more about my favorite trees.

Black Walnut Tree Losing Branches

Hi! I have a very large, tall black walnut tree at the front of my house -near the drive way. It has no signs of disease or that it is dying -- but it is dropping large branches! The branches have green leaves and walnuts and seem to be falling for no reason. Some of the branches have been so large that I have considered taking it down because it is dangerous. Have you ever seen this happen before?

Black walnut dropping branches

We consulted a cooperative extension for your question: The weight alone of walnuts typically does not cause limbs to crack and fall. There may be an underlying pest or disease problem. How old is the tree? Do you see any yellowing or dying leaves? There is a disease of walnut trees called Thousand Cankers Disease caused by the Walnut Twig Beetle recently spotted in Ohio. Following is a link to an OSU announcement about the Walnut Twig Beetle:

Stacy, you can consult a cooperative extension service in your area. Click on your state for details:
It may be that you need to consult an arborist.

Good luck!


Early frost

I have a walnut tree that was starting to leaf out this spring, when we received bitter cold weather and heavy wet snow for 3 days. The leaves turned black and crisp. Now it's the first is September and it has no leaves at all. I've been keeping suckers trimmed along base. I fertilized the tree with deep root waterer this summer. It still is green when I knock it. Am I wasting my time? Or may it come back next spring? It was beautiful last year. Also I have bulbs, bleeding hearts, cosmos, California poppies growing underneath. I miss my tree. Thank you

Fail to leaf after spring frost

This one is beyond our ken, E, but we found some information that may shed some light on your tree’s failure to leaf. (Sit down; there’s a lot to read.)

This page, from the Oregon State cooperative extension service addresses frost situations and more:

Purdue says plainly: “Black walnut is very susceptible to light freezes…” See here:

You can, and should, consult your local cooperative extension service for local advice. See here and choose your state:

Walnuts planted in 1972

Planted 100 seedlings in 1972, then another 3,500 in 1987, of which over 1,000 (drought year in 1988) are still alive and now growing well. This article says the seeds are sweet and two to three inches. Black walnuts have a strong, bordering on bitter, flavor, and in my experience average about an inch in diameter. Some say that they are a slow growing tree. I've got some second-generation volunteers now approaching 50 feet in height, had to remove one second generation tree last year that measured over 20 diameter at the base, about 40 feet through the crown. The hard shell may well protect the nuts for storage, but they must be protected from mice that will chew right through the shell, even chewing through the walls of a plastic container to get to them. Nuts planted in the fall will often sprout the following year, as the shell opens along the seam. Squirrels will "discover" the new seedlings and pull them to get at the nut, although they are also responsible for burrying more nuts than I've ever planted.

Black Walnut tree leaves

Composting: Can you compost the leaves? There was a study that OSU did. That they were safe to compost. They lose the juglone over time of composting.
The one thing is can you put that compost around tomato plants?

black walnut compost

As you mention, juglone is the substance in black walnut trees that can cause severe damage and even kill solanaceous crops (tomatoes, potatoes, peppers and eggplant). However, not all plants are susceptive to the chemical. Edibles that are tolerant of juglone include corn, beans, onions, beets and carrots.

Other trees that carry juglone include butternut, hickories, and pecan; black walnut has the highest concentration of it.

Walnut leaves can be composted because the juglone toxin breaks down when exposed to air, water and bacteria. The toxic effect can be degraded in two to four weeks. In the soil, breakdown may take up to two months after the living walnut tree has been removed. Mulch or woodchips from black walnut are not recommended for plants sensitive to juglone. However, composting the woodchips for a minimum of six months allows the chemical to break down to a safe level even for plants sensitive to juglone.

Black walnut's outer shell

This article, the comments and your well-stated answers were a joy to read. My question is why does the hard green outer shell have such a pungent citrus smell?

Something to Ponder....

I have a larger mature black walnut tree in my garden. I have had wonderful luck with Hostas and most spring bulbs. I have tulips, daffodils, iris and hyacinths. There are several guides for tolerant plants.

Then I tried putting in a KOI POND.....Walnut trees kill fish. Does anyone know if they are safe for frogs????

Black Walnut Tree Toxicity

Hi Michelle,

We’re sorry to hear about your koi pond! It’s hard to say for sure if the black walnut tree toxins will affect frogs: It is poisonous to dogs and horses, but not to cats. The area of affected soil is usually 50 to 60 feet surround the tree, depending on its age. 

increase in the amount of spring unisex flowering??

this year we have an extreme amount of the green flowering type of powder like strings falling from the trees. Does the increase of this make an increase in the the likely amount of nuts they will produce?


Need to know if they will grow by Black walnut trees !!???

The Short Answer

Hi, Marie: Need to tell you nope, not well. Thanks for asking!

We were told by a tree

We were told by a tree trimmer that black walnut trees are subject to emerald ash disease, and that we should get something like ash borer treatment (not sure that is the correct wording) for it. Is this true?

black walnut and emerald ash borer

Emerald ash borer is apparently a threat to black walnut and other trees in much of the country. We are not qualified to comment on treatment; we advise that you consult with an arborist. Your local cooperative extension service may be able to help you identify one; find your state and click here for coop extensions:

FWIW, this page identifies numerous treatments for the EAB, as it is often called:

We do not and cannot recommend or otherwise give any judgment on the products mentioned on that page; we provide it only for your general information.

We hope this helps!


Black walnut trees EVERYWHERE!

I have more than a dozen black walnut trees in my yard. I would love to have a veggie garden or plant some rose bushes or fruit trees. I am open to any plants that will grow. I live in zone 7(a). What will grow in my yard with these trees surrounding me!?

black shadow

Wow, that’s a great question, but it is not one that we are prepared to answer. We do not know what your options are, but we can recommend that you contact your local coop extension service (usually part of a college or university) or a local nursery. You could have a specialist come to see your site, but that might incur expense. No matter what course you take next, it is not going to be easy making choices or decisions. Give yourself time…do it once, the way you really want it.


I moved into an old farm house w a couple black walnuts on the property. I haven't tried to grow anything near my trees. But, there were already established black mulberry and honeysuckle tree/bushes in the same area. The mulberry and walnut touch branches. They are around a car length apart. I have harvested the nuts for baking and made wood stain from the hulls.

I built 2 raised vegetable

I built 2 raised vegetable garden beds (filled with a mixture of compost, sand and peat moss) near my mature black walnut tree and have had no issues with anything struggling to grow. It's not close enough to be under any of the branches (obviously shade isn't great for growing vegetables anyway) so I would imagine a vegetable garden would be fine as long as you're growing the vegetables in "fresh" soil and not soil shared by the walnut tree roots.

Natural growth of walnut tree

Hi. I am wondering if left on the ground will a walnut, even with the husk on, eventually take root if all the conditions are optimum? Would the rotting husk give way to a shoot coming through the hard shell? How does it work? How long would it roughly take from new nut on ground to seedling or sapling stage? Thank you!


It is possible but not probable and it would take a very long time–possibly years for the shell to break down atop the soil (and the likelihood of the nut staying put for that long is slim); burying it speeds up the process due to moisture and microbial activity in the soil. Taking off the husk further speeds the process.


I've heard that planting the whole husk will help break down the walnut for germination. Not sure if this is accurate and have never tried it. I would consider attempting both to see if there is a noticeable difference.

Yes. Seeds in the ground will

Yes. Seeds in the ground will just sprout and grow. We have dozens of black walnut trees on our property. My yard is basically a walnut nursery. I have hundreds of them all over the place. The previous owners just let the nuts fall. I'm sure many of them have been mowed down year after year. Either way, yeah, stick them in the ground and they will grow! It probably does take a few years to cold stratefy and break through the shell.

Yes. Seeds in the ground will

Yes. Seeds in the ground will just sprout and grow. We have dozens of black walnut trees on our property. My yard is basically a walnut nursery. I have hundreds of them all over the place. The previous owners just let the nuts fall. I'm sure many of them have been mowed down year after year. Either way, yeah, stick them in the ground and they will grow! It probably does take a few years to cold stratefy and break through the shell.

Planting near black walnut tree

What if any plants can grow well near black walnut trees. I have a very large side-yard that I would love to fill, but am not sure what will live near this tree. I have already lost many plants and trees due to not knowing about this problem before. Any information or advice would be very welcomed!

Compatible plants

There are many plants that tolerate the toxicity of black walnut. Perhaps you could help to narrow down our list by telling us if you are looking for trees, shrubs, perennials, or annuals. Happy to assist once we know what you’d like to plant.


I noticed the soft outer

I noticed the soft outer shell of Black Walnuts degrade fairly quickly so I heaped tons of the nuts on my compost pile. Are they toxic to my compost?

Numerous Black Walnuts this year

We have lived in this house in Kansas, west of Kansas City, on 10 acres for almost 20 years and we have never seen this many walnuts. I picked up over 100 lbs from one tree without even trying. The limbs are breaking off because of the weight of all the walnuts. I was curious why this year there are so many and is there a correlation to the severity of the winter and the number of walnuts? We did have a wet spring so they were well watered and probably had lots of pollination of the fruit. We were trying to see if there was on old wives tale if this meant a bad winter :) We just wish we liked to eat Black Walnuts like we do English Walnuts. :) Is there a way to make them more palatable since we have so many or something else to do with the nuts? Is there a quick way to pick them up because we had a friend fall from stepping on one in the driveway and it rolled under his foot? We have to be careful walking around the property doing work because there are areas that are solid walnuts! Thank you for any information you can provide. DB

Black Walnut Overload

It sounds like the confluence of climate conditions made your trees exceptionally happy this year. To get them up off the ground, it might be worth investing in a very large plastic lawn rake–they make quick work of large swaths of ground; use a snow shovel to scoop them up and into a wheelbarrow or trash can once you have made piles. As to what the heck to do with all of them–consider baking with them. There are many sweet baked good recipes that call for black walnuts–and we all know sugar makes everything taste better!

Baking with Black Walnuts

Thank you so much for your reply! I think we'll try the baking/sugar idea :) I'll let you know. If you are anywhere near the Kansas City area, I'll be glad to get you a 5 gallon bucket for all your holiday baking needs :)
Thanks again

Black Walnut trees have a

Black Walnut trees have a slow growing cycle...they will be the first tree to loose its leaves in autumn and the last tree to get leaves in the spring. It has been my observation over the years that they produce nuts on a cycle. It seems like every 5 to 7 years they produce a bumper crop of nuts, then the following year almost none at all...then progressively more and more with each year. If you have an over abundance of nuts this year...chances are that next year you will not have as many.

Overactive black walnut tree - can it be slowed down?

A couple of years ago, my tree dropped a lot of walnuts, but this year it is completely out of control! Yesterday and today, I've picked up over 16 5-gallon buckets full of walnuts off my lawn. I dump them over in a wooded area next to a stream so the wildlife can enjoy them. I didn't know if either a good climate or a bad climate (maybe the tree goes into distress and figures it must reproduce as much as possible) is the reason. Also wondered if because the squirrels climb the tree and eat the walnut, it just keeps producing more and more and more!

A couple of large limbs also broke off yesterday too.

Is there any way to slow this production down? I live in SE Michigan.

black walnuts

these nuts are toxic my puppy ate one that dropped in my yard she got very sick from it how come squirels do not get sick but dogs do i hate those trees

Black walnut tree

We have one that just popped up in our yard a few years ago. I did not know that it is toxic. Will it harm our septic tank, well and dogs

Care Advised

Hi, N: A lot of this depends on where the tree is located. They do have extensive root systems, but then again, most septic systems are built to withstand root pressure. Juglone, the toxic substance exuded by the roots, has a limited “shelf life,” so its effect on a well would not necessarily be dangerous. How the well is lined enters into it, too. Black walnuts–“fresh” and especially after they have decomposed and begun to mold–have been known to have deleterious effects on dogs, so it’s best to keep the two apart. Thanks for asking, and good luck!

this page gives a lot of

this page gives a lot of information on black walnuts.

Leaf Cycle

I am getting married in my parents backyard and we are trying to pick a date. There is a big black walnut tree and I would love to get married when the tree is full of it's vibrant green leaves. I would like to avoid when the tree is dropping leaves and nuts. If you could tell me what months the leaves start to come back and when they start to change color and fall off that would be incredibly helpful.

Also, the tree is in

Also, the tree is in California.

Walnut Trees after El Nino

I have a wedding next June in a walnut grove. I'm wondering how El Nino and a wet winter/early spring will affect the look of the trees for the time of the wedding. Will the trees be green and leafy at that point? Or will it be bare?


Walnut Bliss

Hi, Melanie: To a small extent this depends on where you are, but it’s hard to imagine a scenario in which walnut trees are bare in June… You should be fine. Good luck!

I have a question I've been

I have a question I've been unable to find an answer to, as of yet.

I have three large black walnuts around the edge of my wooded property, but because of the overhang they drop over almost all of the large back yard. (It's dangerous to walk around come autumn.)
I -had- planned to build a small pond in my garden back there, but am now concerned (having recently learned about juglone and why so many rooted things were dying nearby) that the water will be constantly tainted by fallen, toxic debris. The pond was intended for not only aesthetics but to encourage tadpoles, turtles and give the local deer who frequent my yard a recirculating drinking hole. Bad idea?

Hi, PSG: This is a

Hi, PSG: This is a fascinating question. As you know, juglone is nasty stuff, but it is associated mainly with black walnut roots. Because it is not readily soluble in water, it does not travel well or far in soil. As you also know, it does indeed occur in the leaves, bark, twigs, etc., but in concentrations far lower than in the roots. Once it's exposed to air, bacteria, and/or water, juglone will deteriorate within 2 weeks to 2 months. Your question is about its effect on other organisms. To some extent, this would depend on the size (volume) of your pond; by the same token, if all of the "toxic debris" remains near the top, where the creatures are, then their exposure to it might be disproportionate to juglone's overall concentration level. Also, this might depend on the "order" of the species being affected, harbinger species such as frogs being much more susceptible to harm than deer, for example (which, if they get sick once, are not going to come back for a second sip). Is this pond a bad idea? Not necessarily. The juglone is not going to reach it through the soil. Have you thought about doing a small test pond first (or actually one small test pond divided in half physically, perhaps with netting over half) to see if you can see any difference in the flora/fauna? Good luck!

We have several black walnut

We have several black walnut trees and the nuts are turning and falling already. I am talking about a huge amount are coming down. What would cause this happen. We have had a rainy summer. And every tree is loaded.

Excessive rain during late

Excessive rain during late spring or early summer pollination causes poor or no pollination of female flowers. Then the nuts won't form or they will drop early as yours did. Pests and disease such as anthracnose can also cause trees to drop nuts early; you'd want to check the health of your tree. Good luck!

I live in Western North

I live in Western North Carolina, Asheville area. I have noticed several black walnuts are dropping the nuts alreay and its not near time. Any ideas, this is on several properties I see this happening? Thank you Laurel

Hi, Laurel: Early nut drop

Hi, Laurel: Early nut drop can be caused by any number of things, including the tree just trying to limit itself to the optimum amount of fruit. Assuming that disease and soil conditions aren't contributing to this, the most likely cause is often bad or insufficient pollination, one of the main causes of which can be a very wet spring. In your case, spring was rather dry--except for April, which had 2 inches more rain than normal, which is a lot. Let us know if you observe anything else!

I planted 2 English walnuts

I planted 2 English walnuts about 4 years ago they were bare root about 8' tall. they are about 15' tall now but all I ever get is tiny little what looks like walnuts in the spring. but they do not grow any bigger. Are they the walnuts that should get green and drop in Oct.? Thanks Larry

Hi, Larry: The most common

Hi, Larry: The most common cause of this is damage from spring cold or frost. If that is not a possibility and the trees otherwise seem healthy, the only thing to do is wait until they mature more. Sometimes an English walnut can take 6 to 8 years before it sort of "gets its feet under it" and begins to produce "normally." Thanks for asking!

We have a very mature (100+

We have a very mature (100+ years) black/english walnut tree. We are in the 4th year of a historic drought and I've noticed that this year, nearing the end of June, the tree has produced very few leaves. Normally it is leafed-out in May. Could this be a result of the drought and do you think there's a chance for recovery when rainfall normalizes? Thanks.

Black Walnut tree not leafing totally in late June.

Black Walnut tree not leafing totally in late June. If it is drought causing it can it recover? What can I do to help?

My neighbor has a large black

My neighbor has a large black walnut tree that is very close the our property line. There are been saplings that have turned into trees on our property line, destroying my fence. I continue to have saplings popping up in my yard, and have to pull them every week. I am very frustrated with this tree but understand my neighbors need for shade in Arizona. How far does the root system go down below ground level? I am considering digging a trench on the property line and putting a metal roofing or similar barrier to prohibit the roots traveling into my side of the yard and saplings appearing. However, I don't want to go through all the trouble and labor of digging it myself if the trees roots go very deep, and the barrier will do no good. If this barrier will do no good, what do you suggest? This tree is driving me crazy! Thank you so much.

It is unclear from your

It is unclear from your question why you would dig a trench. The saplings come from the nuts and this whole "toxic" thing is very mis-leading. The trees grow in harmony with other things in the forest. It is just a very small number of plants that they do not get along with. But to get back to the root quest, yes, as a hardwood, they have quite an extensive root system, it will extend out beyond the drip line.

black walnuts

i dont think they are black walnuts for they dont grow in arizona

We have 3 large black walnut

We have 3 large black walnut trees. This is the first year that they are dropping the newly forming nuts in the spring. We are a little concerned as to why this is happening. Can you help?

Hi, 3D: This could be from

Hi, 3D: This could be from any number of things, including some sort of infestation. Another thing that happens is that unkind weather conditions interfere with spring pollination, so the weakened tree starts dropping nuts. About all you can do is observe carefully as time goes on and see if anything seems to be afflicting the tree. Otherwise, hopefully it should be stronger next year.

Two years ago I had an old

Two years ago I had an old black walnut cut down and the stump ground up. I now would like to plant veggies there. Do I need to remove all the chips or can I mix in soil and plant that area. The mound of chips has shrunk by 3/4 over the past 2 years. Is it still toxic?

Hi,somewhere I read that you

Hi,somewhere I read that you can use black walnut for fence posts. Questions: does the toxicity apply to fence posts and if you cut down the tree, how do you destroy the toxicity?
Thank you.

Nice blog!yes black walnut is

Nice blog!yes black walnut is beautiful and herbal medicine tree.Dried Walnut Hull or its extract helps in relieving asthma, cough, and chronic bronchitis. Regular consumption of this herbal extract offers excellent relief for people of age suffering from chronic respiratory diseases. In Asian countries the use of black walnut and its extract a popular home remedy for treating respiratory diseases. Check out the Benefits of Black Walnut here: buytincture which is best herbal store.

We just purchased some land

We just purchased some land that is covered in black walnut trees. We will be taking some down to plant grass and do landscaping. How long are the roots toxic after they ate cut down?


Hi, Susan: The duration of

Hi, Susan: The duration of the toxicity of juglone, the poisonous agent of black walnut trees, really depends in some part on the type, density, and drainage of the soil (although juglone is not very soluble). Still, it can last for 5 or 6 years or even longer -- and it can be much shorter, too. There are two things to do: (1) When you "stump" (pull up the stumps on) your land, try to get as much of the big roots as possible, even if it means a little more work. They have a massive root system, but every little bit that's not there helps. (2) Research online or at your library what plants are tolerant of juglone -- there are quite a few: Kentucky blue grass, for example. Good luck!

I have a few acres of black

I have a few acres of black walnut trees. Unfortunately they were planted about 10 feet apart so they have grown tall and thin. They are about 50 feet tall with trunk diameters of 6-12inches. I'd like to thin some areas in hopes that the trees will branch out and spread at the crown. Is it too late for them or will opening the area encourage them to branch out?


Hi, Corinna: This is a good

Hi, Corinna: This is a good question, with answers so complicated that we dare not go there. Some of this depends on the purpose of the trees (harvest anything? shade? beauty?). In any event, walnut trees with this extremely tight spacing are best thinned when their diameters are 3 to 4 inches, not 6 and up. Your local climate and soil conditions might come into play, too, not to mention the extensive root systems. We recommend consulting with a professional arborist. Good luck!

Poison ivy vines are growing

Poison ivy vines are growing exclusively on all my walnut trees in the unkept, mature woods of the older home I just bought in northern MD. Wild grape, oak, and rosa flora vines are grwing on all the other trees but never on the walnuts. Why? I love and hate it. How agressive can I get with herbicides and not hurt the trees?

Hi, Mary: This seems to be a

Hi, Mary: This seems to be a question not only of arboriculture, but also of semantics. Why poison ivy is not growing on your other trees, we don't know. Why the grape, etc., are not growing on your black walnuts is because b-w's produce an herbicidal substance called juglone (see our intro above) that is toxic to many plants. It is not toxic to poison ivy, which is why p-i will grow on black walnuts. In and of itself, a good (p-i specific, if possible), organic herbicide is not going to kill the trees. In and of itself, it is also not going to kill the p-i vines. The thing to do is first to thoroughly cover every inch, nook, and cranny of yourself with protection from p-i's urushiol oil. Let us repeat that: Cover yourself totally. Then carefully remove (cut out) sections (a foot long is good) of the vines, which will kill what is above (but the oil will still be potent for a year or two). Then, focus on spraying what is below the cut. Carefully discard the cut sections in a way that no one can touch them or what they have touched. By the way, though: Poison ivy leaves are edible by quite a range of wildlife. It's a complicated situation, and no doubt this reply has just scratched the surface.

I just recently found out I

I just recently found out I have a black walnut tree in my next door neighbors home right on my fence line. It drops these green balls onto my roof and scares the crap out of me lolz...I grabbed one today threw it on my cement patio it broke the green ball and I seen it was a walnut shell on the inside. Now I live in northern illinois and my neighbors never planted the tree. How the heck is it surviving?

Normally, you need a special

Normally, you need a special tool to crack a black walnut shell (that is stronger than a common nut cracker) but I guess you found a creative solution! :-) Inside is a sweet nut that you can eat or make into pies.  The tree may have seeded itself; it's hard for us to know. Just keep in mind that the area near the tree can be toxic to other plants and vegetables, so something to keep in mind when you consider whether you want to keep it.

I have a whole yard full of

I have a whole yard full of black walnut trees and a garden right next to one and my plants don't get toxic as a matter of fact I had more tomatoes than I knew what to do with.

We have a Black walnut tree

We have a Black walnut tree in our front yard in Lincolnton, N.C. My question is we have been living here 5 years, and this is the first year it is not bearing nuts. Do they have a non-bearing year like the Pecan tree. Thank you

Some black walnut cultivars

Some black walnut cultivars are indeed prone to alternate bearing or just bearing more heavily every other year.
If your leaves seem unhealthy, here is also a fungus that can effect nut production but can be controlled by fungicide applications. You could contact your cooperative extension for further diagnosis.

My question is when you first

My question is when you first plant your black walnut tree and its only a foot tall,will the deer bite the tops off of them and kill the tree ?

Yes, deer will eat them, I

Yes, deer will eat them, I think it is candy for deer. lol I keep mine fenced until they are about 4-5' tall and the you still need to protect the trunk from deer rubs.

I have or I think I have

I have or I think I have black wallnut trees on my prop. about 35 feet apart. For 15 years I,ve lost many pine trees that I've planted around these black wallnut trees. Is there a pine tree that resists the JUGLONE that was talked about?

I take exception to your

I take exception to your comment regarding Black Walnut pest.
You mention few are out there, we have 17 walnut trees in our back yard.
We live in S.W. Ohio 2.7 miles from a large Veneering company. They are suspect of importing diseased walnut trees from Colorado. We have a major infestation of Walnut Twig Beetles (size of a sesame seed) which carry a fungus which causes 1000 Canker Disease.
Our situation is so bad the state of Ohio Agriculture Dept. has conducted training classes in our yard. We've had Professors from Ohio State University and University of Tennessee investigating and taking samples. Plus the Ohio Division of Forestry Department had 25 of their personal here for observation.
We currently have one of in excess 110 traps around the county. These traps are not to catch the beetles for disposal rather they are for verification of the infestation in other areas.
It's now up to us to take down these dead or dying trees. Then we must figure out a means of disposal without removing any portion including saw dust from the county of which we live Butler County Ohio.
I decided to pass this information on in the event your Walnut trees decided to start dropping leaves early and often all summer long including.

Thanks for your comment. This

Thanks for your comment. This column was written in late 2005 or early 2006 and we appreciate your update.
The walnut twig beetle is a pest that seems to be increasing among black walnut trees (primarily affects black walnut Juglans nigra). Tinier than a grain of rice these beetles carry the fungus Geosmitha morbida that eventually (within a couple or few years) infects the tree and starves it to death. See:
Disposal of the remains can be a complicated and costly procedure.

Do you need to fertilize the

Do you need to fertilize the soil and also what pesticide do you need to treat the black walnut trees? Thanks

It would probably depend on

It would probably depend on whether the black walnuts grow naturally in your area. If they do, we'd say you needn't bother fertilizing, unless you are setting up a stand of trees to harvest the nuts or wood, or if the tree begins to look unhealthy. When fertilizing, we'd recommend that you test your soil for nutrients and then contact your county's Cooperative Extension or an arborist to see what fertilizer is needed for your local soil, for black walnuts, and for the age of the tree. Soil pH is best around 6.2 to 7.2.
The same would apply to pesticides. If the tree is native to your area, and you are just interested in the tree as a landscape feature, then it would not need pesticides unless a specific problem arises. If, however, you are planning to harvest, then monitoring for specific pests, such as the walnut husk fly, would be called for, with the appropriate pesticide that is safe for edibles if harvesting the nuts rather than the wood (check with an arborist or your local garden center for what's appropriate in your area).
For more information, you might be interested in the following:

I live in a neighborhood that

I live in a neighborhood that has many mature trees and I have mulitple black walnuts on my property. They are mature but I do not harvest them. The past few years I have been losing many large and small branch's some in storms but most are brought down by the slightest wind gusts. Is this normal? Is there something I can do to prevent it?

This can happen when there is

This can happen when there is too much weight on the ends of the branches. Just prune to thin your trees. Be careful not to overprune or strip the tree on one side or this can cause the tree to get weakened and the branches to bend and break, too.

I bought a large farm 2 years

I bought a large farm 2 years ago (2011) and dicovered about 8 fully grown walnut trees on the edge of the fields in the woods. I am going to try a harvest this year for pesonal consumption. It is august now and was wondering what a good time to and how do I know the best time for harvest. I am in Maryland.

Black walnuts are harvested

Black walnuts are harvested in the fall (mid to late September) once the hull changes from a solid green to a yellowish color and is soft enough that you can dent it with your thumb. The walnuts should ripen on the tree, so you can shake the tree or just wait until the nuts fall. Here is a good reference page on how to harvest and prepare the walnuts:

My neighbor has a huge Black

My neighbor has a huge Black Walnut on the border between our properties. It is exactly where it does us the least good, because it is overshadowing an area that would be perfect for a garden. I call it the "Black Widow Tree".

We have a very old very large

We have a very old very large black walnut. It is a lovely tree but drops yellow spotted leaves all summer. Keeps lawn covered and messy.