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 wide- open, 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. Black Walnut fruits and foliage. 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. 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-it- yourself 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. Perennials Black Walnut Toxicity Hollyhock Alcea sp. Plants Observed to Grow Under Black Walnut Jack-in-the-Pulpit Arisaema triphyllum and Butternut Trees Aster Aster sp. Astilbe Astilbe sp. Trees Lady Fern & Ghost Fern Athyrium sp. Maples Acer sp. Feather Reed Grass Calamagrostis sp. Japanese Maple Acer palmatum Tufted Hair Grass Deschampsia sp. Speckled Alder Alnus rugosa Bellflower Campanula sp. Musclewood Carpinus caroliniana Wild Senna Cassia hebecarpa Common Hackberry Celtis occidentalis Coneflower Echinacea purpurea Eastern Redbud Cercis canadensis Spotted Joe Pye Weed Eupatorium maculatum Pagoda Dogwood Cornus alternifolia Prairie Smoke Geum triflorum Shagbark Hickory Carya ovata Japanese Forest Grass Hakonechloa macra Northern Catalpa Catalpa sp. Daylily Hemerocallis sp. Hawthorn Crataegus sp. Coralbells Heuchera sp. Honeylocust Gledistsia sp. Many Hostas Hosta sp. American Plum Prunus americana Bottlebrush Grass Hystrix patula Ornamental Pear Pyrus calleryana Siberian Iris Iris siberica Oak Quercus sp. Shasta Daisy Leucanthemum sp. Willow Salix sp. Great Blue Lobelia Lobelia siphlitica Elms Ulmus sp. Virginia Bluebells Mertensia virginica Shrubs Beebalm Monarda sp. Barberry Berberis sp. Sensative Fern Onoclea sensibilis New Jersey Tea Ceanothus americanus Cinnamon Fern Osmunda cinnamomea White Fringetree Chionanthus virginicus Peony Paeonia sp. Dogwood Cornus sp. Phlox Phlox sp. American Hazelnut Corylus americanus Obedient Plant Physostegia virginiana Daphne Daphne sp. Solomon’s Seal Polygonatum sp. Euonymus Euonymus sp. Christmas Fern Polystichum sp. Forsythia Forsythia sp. Lungwort Pulmonaria sp. Witchhazel Hamamelis sp. Rudbeckia Rudbeckia sp. Rose of Sharon Hibiscus syriacus Hardy Salvia Salvia sp. Smooth Hydrangea Hydrangea arborescens Stonecrop Sedum sp. Oakleaf Hydrangea Hydrangea quercifolia Goldenrod Solidago sp. St. John’s Wort Hypericum perfoliatum Lamb’s Ear Stachys sp. Kerria Kerria japonica Purple Meadow Rue Thalictrum dasycarpum Lilac Syringa sp. Spiderwort Tradescantia sp. Most Honeysuckles Lonicera sp. Ironweed Vernonia fasciculata Sumac Rhus sp. Vines Rugosa Rose Rosa rugosa Clematis Clematis sp. Willow Salix sp. Engelmann Ivy Parthenocissus quinquifolia Elderberry Sambucus sp. var. Engelmann Most Viburnums Viburnum sp. Bittersweet Celastrus scandens Groundcovers Honeysuckle Vine Lonicera Bugleweed Ajuga reptans Thicket Creeper Parthenocissus inserta Wild Ginger Asarum canadense Conifers Sweet Woodruff Galium odoratum Arborvitae/White Cedar Thuja sp. Pachysandra Pachysandra terminalis Juniper Juniperus sp. Stonecrop Vinca minor Canadian Hemlock Tsuga Canadensis Updated 2015 Black Walnut Toxicity.