Walnut Trees Can Harm Nearby Plants—But These 6 Thrive When Grown Beneath Them Black walnut trees emit a compound that is harmful to some plants—but not these. Close Credit: seven75 / Getty Images The black walnut tree (Juglans nigra) is well-loved for its beauty and the walnuts it grows. However, the roots of this tree produce juglone, a chemical released in the soil surrounding the tree that can be problematic for nearby plants. Laura Irish-Hanson, horticulture educator at the University of Minnesota Extension Jerry Henkin, president of the New York Nut Growers Association The Plant Clinic team at the Morton Arboretum Nightshades (tomatoes, potatoes, peppers, etc.) are at the biggest risk of juglone poisoning, displaying symptoms like yellow leaves, poor growth, and death. Asparagus is another plant that tends to be affected. "Alliums or other edible plants do not do well due to the juglone," says Jerry Henkin of the New York Nut Growers Association. Some annual flowers fail as well. If you have these trees in your landscape and you want to add a few understory plantings, we spoke to experts who called out some varieties that can thrive beneath black walnuts. According to the Plant Clinic team at the Morton Arboretum, the allelopathic effect of black walnut has not been studied extensively in recent years, and lists of juglone-tolerant plants may be incomplete. 8 Plants to Always Grow Under Fruit Trees for Fewer Pests, Healthier Soil, and More 01 of 06 Blue Flag Iris Credit: Tungalag Balzhirova / Getty Images For late spring charm, it's hard to top the blue flag iris (Iris versicolor), with its bluish-purple blooms accentuated by yellow stripes. They like a bit of moisture in the soil, similar to black walnut trees, so their needs are similar, and they can tolerate and even thrive in some shade. The blooms of blue flag iris are lasting and prolific, so they're a great perennial to add to your landscape. Zones: 3 to 8Size: 2 to 3 feet tall x 2 to 3 feet wideCare requirements: Full sun to partial shade; moist or even damp soil 02 of 06 Hostas Credit: Marina Kositsyna / Getty Images The array of options in the Hosta family is extensive and beautiful. Many hostas thrive in shade, which makes them an appropriate choice to grow near or under trees. Henkin says hostas are fine for growing near a black walnut tree and can withstand exposure to juglone. Zones: 3 to 9Size: 4 to 36 inches x 6 to 60 inches wideCare requirements: Full to partial shade; well-drained soil 03 of 06 Ferns Credit: Feifei Cui-Paoluzzo / Getty Images If you love delicate foliage and brilliant greens, ferns can be an eye-catching addition to your lawn or garden, and they generally seem to be tolerant to juglone. "I’ve had ferns under a black walnut, and they survived fine," says Henkin. Zones: 3 to 11Size: Varies widely depending on the varietyCare requirements: Full to partial shade; well-drained soil 04 of 06 Jack-in-the-Pulpit Credit: KenWiedemann / Getty Images Jack-in-the-pulpit (Arisaema triphyllum) is so unique and makes a great conversation starter in the garden. It grows only about 1 to 2 feet tall but possesses a fascinating leaf-like blade that grows vertically and leans over the unusual blossom. These plants love the shade and moisture, and they're not affected by the juglone from walnut trees. Zones: 4 to 9 Size: 1 to 2 feet tall x 1 to 2 feet wideCare requirements: Full to partial shade; moist, fertile, well-drained soil (no clay) 05 of 06 Aster Credit: Salomatin / Getty Images There are many varieties of asters in stunning hues, from blue to pink to purple to white. No matter the type you choose, aster will bring late-season charm to the garden landscape and can withstand exposure to juglone. Plant them in the sunnier areas around your walnut trees, as they need sun to thrive. Zones: 3 to 9Size: 1 to 6 feet tall x 2 feet wideCare requirements: Full to partial sun; well-drained soil 06 of 06 Black Raspberries Credit: Getty / Caytlin Endicott While walnut trees can kill some edible plants, there are types that will survive. "Black raspberries (Rubus occidentalis) can be successfully grown near black walnuts," says Laura Irish-Hanson, horticulture educator at the University of Minnesota Extension. However, she notes that black walnuts cast some shade, so the yield for fruiting crops will be lower. Zones: 4 to 8Size: 3 to 6 feet tall x 4 to 8 feet wideCare requirements: Full to partial sun; moist, organic-rich soil Explore more: Garden Landscaping