Many gardeners plant black walnut trees for shade, for the nuts they produce and for their valuable hardwood. Landscaping with black walnuts can be a challenge, however, as they make a substance called juglone that is toxic to many plants. Any plant within the drip line of a black walnut tree must be able to withstand constant exposure to this substance. Fortunately, a number of plants are able to thrive near black walnut trees.
Not many vegetables handle planting near black walnut trees, but a few key crops do well. According to Purdue University Cooperative Extension Service, lima beans, snap beans, beets, corn, onions and parsnips tolerate juglone. The Iowa State University Extension Service also adds carrots to this list.
Many shade-tolerant flowers tolerate planting near black walnut trees. According to the Morton Arboretum, trillium, ferns, Jack-in-the-pulpit, bluebells, several types of iris, begonia, pansies and violets all thrive in the shade of a black walnut tree. A number of bulbs---including daffodil, daylily, crocus, tulips, snowdrops and hyacinth---are also considered immune to juglone's effects. Unfortunately, poison ivy also tolerates black walnut trees.
Most fruits are adversely affected being near a black walnut tree. Some that tolerate juglone, however, are cherry trees, black raspberry bushes, some melons, wild grapes and currants. According to the Ohio State University Extension Service, nectarines, peaches and plums also do well.
Certain types of grass do better near black walnut trees than others. According to the University of West Virginia Extension Service, these include fescue, Kentucky bluegrass, red top grass, timothy and orchard grass.