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once cut down, how long are Black Walnut roots toxic?

Posted by Lowville5 5 (My Page) on
Fri, May 18, 12 at 9:03

This is my first posting. Last week my husband cut down a black walnut tree because we had 3 beautiful young trees and several perennials die last year that were very close to the black walnut. I don't know if it is related, but last summer a storm broke off a huge section of the BW. Would that stress have caused the BW to send out more juglone? Unfortunately when I had planted those trees & perennials, I did not know about this website! Consequently, I had planted all the wrong species very close to the BW. Now that the BW has been reduced to a 1 foot tall stump, will my new plantings survive? I did choose species listed in this forum as being BW tolerant.

I have not been able to find any posting that lists tolerant annuals I could plant while waiting for these perennials to fill out. The stump is the first thing you notice when coming down our driveway! Any advice would be much appreciated.

We do have another BW 25 feet away that I have never planted anything around it. Should we cut it down now as a preventative measure?

I have learned so much from this forum in the past month. I wish I had known about it a few years ago when I started gardening. I would not have made so many costly mistakes. I'd really like to thank all of you generous gardeners for the time and energy you invest helping us newbie gardeners.


Follow-Up Postings:

RE: once cut down, how long are Black Walnut roots toxic?

  • Posted by ging 7a (My Page) on
    Wed, May 23, 12 at 20:29

Hi Jennifer,
I found a good site with the info you're looking for - it's not good. It says that the toxicity can last for years as the dead roots are still releasing juglone. I'm adding another address that had some rather startling info on the root/toxicity zone. It was a lot larger than I thought. That would be in the Ohio link here:

Hope this helps and wish the news was a bit better,

Here is a link that might be useful: Black Walnut Toxicity

RE: once cut down, how long are Black Walnut roots toxic?

  • Posted by artdeco 5 - Chicago burbs (My Page) on
    Mon, Jun 4, 12 at 2:05

If your husband is willing to cut it down for you - do it!
And then plant 1 or 2 squirrel friendly trees in its place - such as Oak or Horsechestnut.

Our yard is surrounded by huge BW trees, so I understand your frustration. Even more frustrating is seeing little trees planted by squirrels, sprouting just beyond our fence in our neighbors yard, and they aren't removing them. Soon our yard will be a complete network of BW roots.
If you remove all your BW trees, you are reducing the odds of more trees appearing in the future at the other end of your lot which is currently juglone free.

I too have read that the juglone can persist for many yrs after a tree is removed, but if you plant only tolerant plants now, eventually you can work in others. Time flies so fast - before you know it 5 yrs will have passed!

If you leave the remaining tree, the roots will eventually travel much further than 25 ft. - this spring I found many pencil-sized roots just 6" below the surface from a neighbors tree >60' away. Cornell Univ found roots can grow 3 times the spread of the canopy.

I had planted yews in an area I thought was safe - they did great for years til 2 started dying, & I found walnuts buried inches from their trunks. So last fall I dug-out a whole row of 3' yews.

Black Walnuts are beautiful trees & serve an important role in nature, but they don't belong in a garden or small yard - they belong in large open areas. There are so many more suitable trees available - why leave a tree to grow that you will resent for all the years you live at this house?

And I haven't found any annuals that flourish under a BW.

RE: once cut down, how long are Black Walnut roots toxic?

I have removed several large black walnuts and the area accepted any kind of ornamental or vegetable by the following year. The poison simply doesn not last.

RE: once cut down, how long are Black Walnut roots toxic?

You should really talk to a sawmill before you take down a large black walnut.... they can be worth quite a bit of money if you take them down the right way (and don't chop em all up to hell).

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