Hello We have a few large black walnut trees in our yard. Our evergreens have...

Asked January 9, 2015, 9:55 PM EST

Hello We have a few large black walnut trees in our yard. Our evergreens have not grown over the years, and we feel that is the reason. We will be taking down some Hawthorne trees that are not doing well and want to replace that area with tree or shrubs that are not resistant to juglone from the walnut trees. I have contacted 2 nurseries and they sent me lists but what one lists says is tolerant, the other list says is not tolerant for some of the plants, Do you have any suggestions of a nice tall shrub or tree that would look nice and be a good barrier to road noise ( we have 5 trees there now). It faces south and gets good sun. Somebody suggested arborvitae but I was thinking some more like a row of colorful virburnum, but again conflicting reports on their tolerance. Thank you in advance. Carol Youdas

Olmsted County Minnesota black walnut tree

1 Response

It can be frustrating when the "experts" don't agree on all of the answers. Often times the best bet is to choose the answers that they Do agree upon.

The chemical, Juglone, is the culprit here. This chemical will affect sensitive plants anywhere within the root zone of the black walnut - and to be safe - you should consider another 10 feet or so beyond that to avoid the effects. You have not said how large the black walnuts are, nor how much of your planting space is impacted by their roots but tree roots grow outward - not down. They extend at least as far as the spread of the leaf canopy. A large black walnut may have a canopy of over 40 feet in diameter!

Here are a couple of links from our university extensions that explain the problems, and suggest some best practices, and some plants that may do well with black walnuts as neighbors:

http://www.wvu.edu/~agexten/hortcult/fruits/blkwalnt.htm

http://hort.uwex.edu/articles/black-walnut-toxicity



I hope this is helpful. Thanks for contacting AaE!