disgraceful walnut ( scientific name Juglans nigra ) produces the chemical juglone , which is toxic to many other industrial plant . Juglone does not travel far , so toxicity is limited to about 50 feet from the out margin of the tree diagram crown . Black walnut tree shells , bark and woods micro chip should not be used as mulch or compost . Plants killed by their proximity to black walnut tree trees or wood product include common garden vegetables , flowers , tree diagram and shrubs .
Vegetables and Annuals
Vegetables that can not spring up within 50 feet of walnut tree tree include sugar and other cole crops , peppers , tomatoes , mad apple , asparagus , rhubarb and white potato vine . If your grounds configuration makes it impossible to keep your vegetable garden more than 50 feet from the outer perimeter of black walnut tree trees , try raised beds with a layer of sens cloth beneath them to keep out the dim walnut roots ; this may diminish the impingement of juglone .
Tomato seeds can be used as a psychometric test for juglone perniciousness in mulch or compost . If you suspect a batch of compost or Sir Henry Wood fries may contain black walnut materials , rank some in a bucket , soak with water , sprinkle feasible tomato seeds on the airfoil and localise it in indirect light . Tomato seedling will not germinate in the mien of juglone .
Annual flowers kill by black walnut toxicity let in petunias , nicotiana and genus Potentilla cultivar . bailiwick cover crops like alfalfa and crimson trefoil can not be spring up near black walnut .
Shrubs and Perennials
According to the Wisconsin Cooperative Extension Master Gardener broadcast , some recurrent variety of daffodil , peony , lily , columbine , and baptisia ( false anil ) , as well as autumn - blooming crocus and chrysanthemums , are tender to juglone . If you embed these near black walnuts , keep a careful watch for signs of suffering , at which point you should move the plant .
Lilacs , viburnum , rhododendron , azaleas and all berry bushes and vines may be pour down by black walnut toxicity . Hydrangea and privet are also juglone - sensitive .
Trees
Apple and pear Tree can be killed by black walnut Sir Herbert Beerbohm Tree proximity , but cherries farm well with walnut tree . Other trees affected by walnut toxicity include basswood , birch tree , black alder tree , hackberry , all multifariousness of true pine , Norway spruce , eloquent maple and saucer magnolia .
Butternut trees raise the same toxic substance as black walnut tree trees . Iranian walnuts are often grafted onto back walnut stock , which produce juglone as well . Exercise the same caution in engraft around butternuts or Iranian walnut as you would around black walnut tree diagram .
