I have a partly wooded backyard with many Black Walnut trees. Many
plants,trees and shrubs won't survive when grown close to them Does any kind
person have experience in growing anything near them?One of the things I
want to plant are hemlock trees nearby. Can anyone give me some advice on
that and/or other trees/shrubs? Thanks. S.
Because of a substance produced by the Black Walnut's roots (called
'Juglone'), many plants will not thrive or even live within their driplines.
There *are* plants that are not affected by Juglone. From
"The following landscape plants have been observed to be tolerant to
juglone: arborvitae, autumn olive, red cedar, catalpa, clematis, crabapple,
daphne, elm, euonymous, forsythias, hawthorn, hemlock, hickory, honeysuckle,
junipers, black locust, Japanese maple, maple (most), oak, pachysandra,
pawpaw, persimmon, redbud, rose of sharon, wild rose, sycamore, viburnum
(most), Virginia creeper."
The roots of Black Walnut (Juglans nigra L.) and Butternut (Juglans
cinerea L.) produce a substance known as juglone
(5-hydroxy-alphanapthaquinone). Persian (English or Carpathian) walnut
trees are sometimes grafted onto black walnut rootstocks. Many plants
such as tomato, potato, blackberry, blueberry, azalea, mountain laurel,
rhododendron, red pine and apple may be injured or killed within one to
two months of growth within the root zone of these trees. The toxic zone
from a mature tree occurs on average in a 50 to 60 foot radius from the
trunk, but can be up to 80 feet. The area affected extends outward each
year as a tree enlarges. Young trees two to eight feet high can have a
root diameter twice the height of the top of the tree, with susceptible
plants dead within the root zone and dying at the margins. The juglone
toxin occurs in the leaves, bark and wood of walnut, but these contain
lower concentrations than in the roots. Juglone is poorly soluble in
water and does not move very far in the soil. [from Ohio State
University Extension Fact Sheet HYG-1148-93 by Richard C. Funt and Jane
At http://www.efn.org/~bsharvy/bwtol.html the Ohio State University
Extension and the American Horticultural Society have reported that R.
nudiflorum, Pinxterbloom Azalea, and Exbury Azaleas Gibraltar and Balzac
will grow near Black Walnut and Butternut trees. They also list many
other plants that will grow in the root zone of these trees.
Pardon my spam deterrent; send email to firstname.lastname@example.org
Visit my Rhododendron and Azalea web pages at:
In New Jersey we had wild cherry trees and wild blackberries growing within
10 feet of some very large (40 ft. tall) wild black walnut trees along a
fence row. This was 25 years ago so I can't remember anything else except
that I had some hyacinths planted over my dead pet rabbit under one of the
trees and they naturalized. Could you try experimenting with some seedling
trees/shrubs to see what happens?
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