Black Walnut Toxicity

Black Walnut Toxicity
Juglans nigra & Juglans cinerea
Identification
Occasionally, clients will call our offices with complaints that
they have an area in their yard where they just can’t seem
to grow anything. One of the questions we ask is “Is there a
black walnut tree nearby?” Black walnut (Juglans nigra) and a
related species, Butternut (Juglans cinerea) produce juglone,
a substance that is poisonous to a wide variety of plants. The
problem exists in all areas of the soil around the trees.
Black walnut and Butternut trees are not recommended
for use in residential landscapes because of the difficulty in
growing other plants nearby. They are best suited to wideopen, natural areas where their beauty and fast growth rate
can be appreciated, their nuts can provide food for wildlife,
and where they will not interfere with the health of other
desirable plants.
They symptoms of juglone poisoning includes yellowing or
browning of the leaves of affected plants, stunted, twisted
growth or a failure to grow, sudden wilting and death. As
Black Walnut and Butternut trees grow larger and their roots
spread, sensitive plants further and further away from the
main trunks of these trees will begin to decline in health and
may eventually die.
Black Walnut fruits and foliage.
Not all plants are affected by this toxicity problem. Some
plants have a natural resistance to juglone and can survive
near and even under these trees. Some plants do not grow
deep roots, and more shallow root systems seem to be more
resistant as well.
Juglone is present in all parts of black walnut and butternut
trees. Care needs to be taken when disposing of the nuts, bark,
and leaves of these types of trees. Do not use these materials
for mulch around plants that are not tolerant of juglone.
We Plan-You Plant (DIY)
Offering the expertise of our Horticulturists, this
custom design service is provided at no cost to you.
This is the best do-it-yourself program if you’re a homeowner
looking to design and plant your own project. Perhaps you
want to add curb appeal to the front foundation? How about
a beautiful mixed perennial bed in the empty corner of your
yard? This program is designed for people who enjoy do-ityourself projects and
can also be tailored to
your capabilities.
Black Walnut form.
www.johnsonsnursery.com • p. 262.252.4988 • Menomonee Falls, WI • Nature’s Best to You.
Black Walnut Toxicity
Perennials
Plants Observed to Grow Under Black Walnut
and Butternut Trees
Trees
Maples
Japanese Maple
Speckled Alder
Musclewood
Common Hackberry
Eastern Redbud
Pagoda Dogwood
Shagbark Hickory
Northern Catalpa
Hawthorn
Honeylocust
American Plum
Ornamental Pear
Oak
Willow
Elms
Barberry
New Jersey Tea
White Fringetree
Dogwood
American Hazelnut
Daphne
Euonymus
Forsythia
Witchhazel
Rose of Sharon
Smooth Hydrangea
Oakleaf Hydrangea
St. John’s Wort
Kerria
Lilac
Most Honeysuckles
Sumac
Rugosa Rose
Willow
Elderberry
Most Viburnums
Bugleweed
Wild Ginger
Sweet Woodruff
Pachysandra
Stonecrop
Shrubs
Acer sp.
Acer palmatum
Alnus rugosa
Carpinus caroliniana
Celtis occidentalis
Cercis canadensis
Cornus alternifolia
Carya ovata
Catalpa sp.
Crataegus sp.
Gledistsia sp.
Prunus americana
Pyrus calleryana
Quercus sp.
Salix sp.
Ulmus sp.
Berberis sp.
Ceanothus americanus
Chionanthus virginicus
Cornus sp.
Corylus americanus
Daphne sp.
Euonymus sp.
Forsythia sp.
Hamamelis sp.
Hibiscus syriacus
Hydrangea arborescens
Hydrangea quercifolia
Hypericum perfoliatum
Kerria japonica
Syringa sp.
Lonicera sp.
Rhus sp.
Rosa rugosa
Salix sp.
Sambucus sp.
Viburnum sp.
Groundcovers
Ajuga reptans
Asarum canadense
Galium odoratum
Pachysandra terminalis
Vinca minor
Hollyhock
Jack-in-the-Pulpit
Aster
Astilbe
Lady Fern & Ghost Fern
Feather Reed Grass
Tufted Hair Grass
Bellflower
Wild Senna
Coneflower
Spotted Joe Pye Weed
Prairie Smoke
Japanese Forest Grass
Daylily
Coralbells
Many Hostas
Bottlebrush Grass
Siberian Iris
Shasta Daisy
Great Blue Lobelia
Virginia Bluebells
Beebalm
Sensative Fern
Cinnamon Fern
Peony
Phlox
Obedient Plant
Solomon’s Seal
Christmas Fern
Lungwort
Rudbeckia
Hardy Salvia
Stonecrop
Goldenrod
Lamb’s Ear
Purple Meadow Rue
Spiderwort
Ironweed
Clematis
Engelmann Ivy
Bittersweet
Honeysuckle Vine
Thicket Creeper
Arborvitae/White Cedar
Juniper
Canadian Hemlock
Updated 2015
Black Walnut Toxicity
Vines
Alcea sp.
Arisaema triphyllum
Aster sp.
Astilbe sp.
Athyrium sp.
Calamagrostis sp.
Deschampsia sp.
Campanula sp.
Cassia hebecarpa
Echinacea purpurea
Eupatorium maculatum
Geum triflorum
Hakonechloa macra
Hemerocallis sp.
Heuchera sp.
Hosta sp.
Hystrix patula
Iris siberica
Leucanthemum sp.
Lobelia siphlitica
Mertensia virginica
Monarda sp.
Onoclea sensibilis
Osmunda cinnamomea
Paeonia sp.
Phlox sp.
Physostegia virginiana
Polygonatum sp.
Polystichum sp.
Pulmonaria sp.
Rudbeckia sp.
Salvia sp.
Sedum sp.
Solidago sp.
Stachys sp.
Thalictrum dasycarpum
Tradescantia sp.
Vernonia fasciculata
Clematis sp.
Parthenocissus quinquifolia
var. Engelmann
Celastrus scandens
Lonicera
Parthenocissus inserta
Conifers
Thuja sp.
Juniperus sp.
Tsuga Canadensis