Black walnut trees are a sight to behold, boasting striking dark bark and feathery leaves that create a dramatic visual contrast against various weather conditions. Not only do these trees produce an abundance of delectable nuts, but they also offer a unique opportunity for homesteaders and small farmers to cultivate their own bounty.
However, this seemingly idyllic scenario is often marred by the presence of juglone, a potent compound secreted by the roots of black walnut trees that can be devastating to neighboring plants. The unwary gardener may find themselves grappling with the unintended consequences of planting black walnuts, only to discover that these trees do not harmonize well with other vegetation.
If you’ve unknowingly introduced black walnuts into your orchard or inherited a property with established trees, you may be left wondering if there’s any way to rectify this situation.
What is Juglone?
Juglone is a toxic compound produced and released by black walnut (Juglans nigra) into the surrounding soil through its roots. This allelopathic compound primarily concentrates in the bark and roots of the tree, but exists throughout its entirety. Studies have shown that juglone disrupts the metabolic and respiratory functions of neighboring plants, causing them to wilt and eventually die within 30 hours of exposure.
The resulting symptoms include yellowing leaves and ultimately, plant death due to juglone poisoning. This phenomenon serves as a clever mechanism for the walnut tree to eliminate competition and secure all available water and nutrients in the soil for itself. As the spread of juglone can extend up to the height of the tree, it’s not uncommon to find large patches devoid of vegetation, a testament to the tree’s ability to dominate its environment.
Should I Cut Down My Black Walnuts?
While some people have attempted to eradicate walnut tree juglone by cutting down the tree, it’s crucial to understand that this approach won’t effectively eliminate the problem. The roots of the tree continue to release juglone into the soil as they decompose over several years, even with proper stumping and aeration techniques. This means that any previously cultivated area now hosting a black walnut tree will remain contaminated with juglone for an extended period.
Fortunately, not all plants are equally sensitive to juglone’s effects. By selecting varieties that are less reactive to the compound, gardeners can coexist with black walnuts and still cultivate a thriving garden. It’s also important to note that other tree species, such as hickories, English or Persian walnuts, and butternuts, contain similar compounds that can affect plant growth.
Flowers & Ornamental Plants Resistant to Juglone
Beneath the majestic canopy of black walnut trees, flowers create a visually striking contrast with their vibrant petals set against the rich, dark tones of the trunk. The unique combination of these two elements is truly breathtaking. To replicate this beauty in your own garden, seek out hardy flower varieties that are resistant to juglone, the chemical emitted by the walnut tree.
By doing so, you’ll be able to create a stunning floral display that thrives in harmony with its arboreal counterpart.
Bee Balm (Monarda spp.)
This perennial powerhouse from the mint family is incredibly adaptable and can thrive in zones 4-9. Its citrusy scent, reminiscent of bergamot, makes it a popular addition to herbal tea blends. Monarda’s rapid spreading ability allows it to quickly fill any vacant space, as evidenced by its impressive growth under the walnut tree. In the summer, the plant bursts into vibrant bloom, producing tiny ‘bonfires’ of crimson, purple, or pink flowers.
Daylily (Hemerocallis spp.)
While some gardeners may view daylilies as nothing more than attractive weeds, the reality is that these resilient plants are capable of flourishing in even the most challenging environments. In fact, their adaptability allows them to thrive across a broad range of zones, specifically spanning from 4 to 9. One of the key advantages of daylilies is their ability to withstand juglone and other potential stressors, allowing them to bloom and spread with ease wherever they’re planted.
Kentucky Bluegrass (Poa pratensis)
Kentucky bluegrass boasts a rich, dark green hue and a soft, lush texture that’s simply irresistible. A hardy and adaptable variety, it flourishes in zones 1-8, allowing for its elegant strands to grow tall and tufted or spread out in a serene, naturalized landscape. Imagine the idyllic scene: your livestock grazing peacefully beneath the majestic canopy of your black walnut tree, its golden leaves rustling gently in the breeze.
Yarrow (Achillea millefolium)
The humble wild yarrow is a treasure trove of delight, boasting delicate white blooms and an abundance of leaves. While its natural hue is serene, cultivators have successfully coaxed vibrant colors from this charming flower. When integrated into a garden landscape, yarrow’s good fortune can be multiplied by pairing it with the similarly auspicious Monarda.
According to folklore, the presence of yarrow can even ward off noxious plants and malevolent entities, allowing its surroundings to flourish in a safe and prosperous environment.
Zinnia (Zinnia spp.)
As summer draws to a close, few things bring greater joy than harvesting a bouquet of vibrant zinnias each week and filling your home with their warm, inviting presence. These bright and cheerful flowers are not only prolific bloomers but also steadfast in their commitment to color, persistently filling sunny spots around your black walnut tree until the first frost arrives.
What’s more, they thrive as annuals in USDA Growing Zones 2-11, making them an ideal choice for gardeners of all skill levels.
Wild Rose (Rosa acicularis)
While it’s true that not all rose varieties thrive in the presence of black walnut, certain types of wild roses possess an extraordinary level of resilience. They’re capable of tolerating conditions that would be challenging for their more cultivated counterparts. By combining these hardy wild roses with walnut trees, you’ll create a visually striking and aromatic display, as the contrast between colors, textures, and scents will be particularly captivating.
Coneflower (Echinacea spp.)
Coneflowers are a stunning choice for cut flower arrangements, offering a statuesque presence that elevates any garden’s visual appeal. Their slender stems and dainty blooms harmonize beautifully with neighboring daylilies and zinnias, while also coexisting peacefully with black walnuts. This versatility makes them an excellent addition to mixed borders. When it comes to their hardiness, coneflowers thrive as perennials in USDA Zones 3-9.
Wisteria (Wisteria spp.)
One characteristic that sets Wisteria apart from other vines is its remarkable resilience. Unlike many plants, Wisteria does not fall prey to the toxic effects of juglone, a chemical compound found in the nuts and leaves of walnut trees. This hardiness makes it an attractive option for gardeners seeking low-maintenance yet visually striking additions to their outdoor spaces.
Hosta (Hosta spp.)
Hostas have long been a go-to choice for gardens plagued by shade. Not only do they bring vibrancy with their showy spikes of blooms during summer and striking foliage from spring through fall, but they also offer an added layer of utility, as young shoots are edible. When planting these perennials, consider situating them beneath the canopy of a black walnut tree, where they’ll thrive in the dappled light and add pops of color to the understory.
Hollyhock (Alcea rosea)
A member of the mallow family, hollyhocks are renowned for their stately, vibrant flower spikes that can reach impressive heights. Within this botanical grouping, hollyhocks stand out for their striking visual appeal.
Pansies and Violets (Viola spp.)
While many flowering plants can be finicky about their surroundings, these vibrant blooms are surprisingly adaptable. Not only do they thrive when planted annually, but they also get along swimmingly with nearby black walnuts, making them an excellent choice for gardeners of all levels.
Vegetables & Fruits Resistant to Juglone
While it’s widely known that tomatoes and apple trees are sensitive to the toxic compound juglone emitted by black walnut trees, many people mistakenly assume that all vegetables and fruits will suffer in its presence. However, there is a group of hardy, juglone-resistant plants that can not only thrive but also produce abundantly when planted near these trees.
Beans (Fabaceae family)
Beans, particularly the well-known varieties, thrive when planted alongside black walnut trees. Both bush and pole bean species exhibit compatibility with the juglone compound found in the tree’s roots, making for a harmonious coexistence.
Beets (Beta vulgaris)
When it comes to companion planting near walnut trees, many root crops thrive. Red beets, for instance, are incredibly hardy and won’t bat an eye at the soil conditions around black walnuts. In fact, golden beets, which can be a bit more finicky, aren’t negatively impacted either. This means you can fill a bed with beets near that old walnut tree without worrying about any adverse effects.
And when it’s time to harvest, simply combine your freshly picked beets and walnuts with some olive oil, crumble in some goat cheese, and enjoy the perfect autumnal salad.
Garlic (Allium sativum)
Garlic is surprisingly resilient when it comes to its growing conditions. Unlike some other plants that are sensitive to certain chemicals or environmental factors, garlic is unfazed by juglone, a chemical compound found in certain tree species like walnut. In fact, you can plant garlic alongside monarda and yarrow, two flowers often used in ‘good luck’ gardens, without worrying about any negative impact on the garlic’s growth.
This makes it an excellent choice for gardeners looking to create a thriving and auspicious garden bed.
Leeks, Chives, Shallots, and Onions (Allium spp.)
In stark contrast to their reputation for being finicky, none of the allium family – comprising onions, garlic, and leeks – experience difficulties when grown in proximity to walnut trees. In fact, these pungent and nutrient-rich vegetables possess a remarkable resilience that enables them to thrive in a wide range of environments.
With this in mind, feel free to create an all-allium extravaganza in your yard, knowing that there’s no such thing as too many of these hardy bulbs – or walnuts for that matter.
Squash (Cucurbita spp.)
Winter squashes display a remarkable indifference to their surroundings, including neighboring plants. In my garden this past summer, the squash vines reveled in their freedom, spreading out haphazardly and climbing over any obstacle that got in their way. This carefree attitude extends even to juglone, a chemical emitted by walnut trees that can be toxic to some plants.
The squashes seem completely impervious to its effects, instead viewing the walnut trees as simply another means of support for their tendrils.
Carrots (Daucus carota subsp. sativus)
Carrots, like their root crop counterparts beets, onions, and garlic, have the ability to flourish in juglone soil. This unique quality makes them an ideal choice for planting around black walnut trees, which can often leave otherwise unused space in its wake. By doing so, you’ll not only utilize a potentially underutilized area but also reap a bountiful harvest of crunchy, sweet carrots.
Cherries (Prunus spp.)
Despite being notorious for their fragility, cherry trees surprisingly exhibit a remarkable resilience to juglone, a compound found in walnut and pecan trees. In contrast, they are susceptible to diseases and pests, making them high-maintenance trees that require careful attention. However, this unique tolerance to juglone is an intriguing aspect of their biology that highlights the complexity of plant interactions.
Wheat
It’s fascinating to note that certain grains tend to thrive in the vicinity of black walnut trees. Research suggests that planting wheat near these trees can be particularly beneficial, as the juglone produced by the tree may even promote increased growth in smaller grain varieties.
Pawpaw (Asimina triloba)
In the autumn, pawpaw trees yield an abundance of fruit, unaffected by the presence of juglone. During the spring, these deciduous shrubs put on a stunning display of blooms, showcasing their beauty.
Persimmon (Diosypros virginiana)
While not as widely renowned as its Asian counterparts, the American persimmon possesses a unique advantage – its resistance to juglone. And when left to ripen on the tree, the fruits become surprisingly succulent and enjoyable.
Elderberry (Sambucus Canadensis)
Elderberries may not be as flashy as some other fruits on the market, but they’re truly remarkable in their own right. Not only do they provide a wealth of nutritional benefits through their edible components – think food and medicine – but they also offer stunning visual appeal during the spring bloom. The vibrant colors and delicate petals are a treat for the eyes, making them a valuable addition to any garden or natural setting.
And let’s not forget about their impressive resistance to juglone, a testament to their hardiness and resilience.
Black Raspberry (Rubus occidentalis)
When it comes to the flavor profile of black raspberries, many would agree that they’re a culinary delight. What’s more, these delicious berries are surprisingly tolerant of being grown in close proximity to their fellow fruit, the black walnut. In fact, there seems to be no discernible issue with cultivating black raspberries alongside black walnuts, making for a harmonious and productive coexistence.
Parsnips (Pastinaca sativa)
For gardeners seeking to cultivate crops that thrive in chilly temperatures, parsnips are a staple. These resilient vegetables not only develop an enhanced flavor profile after being exposed to frost but also remain unaffected by the proximity of black walnut trees. In contrast to many other varieties, parsnips can be grown confidently, even near these otherwise troublesome trees.
Quince (Cydonia oblongata)
Quinces share a fascinating connection with other iconic fruits like roses, apples, and pears. While they may not be as widely consumed or cultivated, quinces boast a unique charm that extends beyond their sweet flavor. The trees’ ornamental value lies in their striking leaves and showy blossoms, making them a popular choice for gardeners seeking to add visual interest.
Corn (Zea mays subsp. mays)
While corn and wheat are often grown separately, an intriguing phenomenon exists: when planted near a plant that produces juglone, corn can thrive. This contradicts the conventional wisdom that corn prefers to be planted alone.
Trees & Shrubs Resistant to Juglone
Those with a passion for trees may breathe a sigh of relief knowing that a solitary black walnut tree will not dominate an entire yard. In reality, there exist numerous stunning tree varieties that can coexist harmoniously with this sometimes unwanted walnut. By embracing a diverse range of flora, homeowners can cultivate a lush and vibrant outdoor space, where the unique charm of each individual tree is allowed to flourish.
Hawthorn (Crataegus spp.)
Hawthorn trees have always held a special place in my heart. The unique combination of their striking thorns, vibrant blossoms, and luscious red berries makes them a stunning addition to any yard. But what I appreciate most about hawthorns is the versatility they offer – not only do they add visual appeal, but their leaves and fruits also make for a refreshing and rejuvenating brew when infused into teas or elixirs.
Much like walnut trees, hawthorns have an inherent understanding of the importance of setting boundaries, and it’s this ability to protect themselves that I find both fascinating and admirable.
Beech (Fagus spp.)
Beech trees have a unique ability to thrive in proximity to walnut trees, which is quite impressive given the presence of juglone, a chemical known to inhibit growth. Despite this, beeches can grow strong and healthy near walnuts, making them an excellent choice for outdoor play areas where kids love to climb and explore!
Linden (Tilia spp.)
The majestic linden tree is a treasure trove of natural wonders. Its stunning wood, prized for carving, yields beautiful creations while its fragrant blooms are a sought-after ingredient in herbal teas. The tree’s foliage also provides a sanctuary for bees and butterflies, offering a haven amidst the hustle and bustle.
As if that weren’t enough, the linden’s vibrant green leaves and delicate white flowers create a striking juxtaposition against the dark, rugged bark of the nearby black walnut tree, which adds an air of sophistication with its sturdy nuts.
Maple (Acer spp.)
The sweet combination of walnuts and maple syrup can be enjoyed to its fullest when these two plants are grown together. While all maple varieties aren’t compatible with juglone soil, sugar and Japanese maples are exceptions. Among the many stunning cultivars of Japanese maple, ‘Bloodgood’ is a timeless favorite that would complement black walnut trees beautifully.
Its deep purple foliage would create a striking contrast to the rich brown hues of the walnuts, making for a visually appealing landscape combination.
Forsythia
When placed near black walnut trees, Forsythia’s vibrant yellow blooms create a striking contrast against the gray-black bark of its companion plant. Notably, this shrub also proves easy to transplant, making it an excellent choice for filling in around walnut trees temporarily. If you’re undecided about what to do with the surrounding area, consider planting Forsythia for a year or two, allowing you to admire the beauty while contemplating your next move.
Juniper (Juniperus spp.)
Eastern red cedar, often mistaken as a true cedar, is actually a type of juniper that thrives in the eastern United States. In contrast, common cedar (J. communis) is native to North America and comes in various cultivated forms available for purchase. Interestingly, any species of juniper can flourish when planted near black walnut. One popular option is the low-growing Blue Star juniper (J. squamata ‘Blue Star’), which is a great choice for many gardens.
Catalpa (Catalpa bignoniodes)
Catalpas boast striking foliage, with enormous leaves that are complemented by similarly impressive seed pods. This unique combination sets them apart from other garden plants. Interestingly, these large-leaved wonders thrive when planted alongside black walnuts and other species that produce juglone, a chemical that benefits their growth.
Sycamore (Platanus occidentalis)
Characterized by their impressive stature, these deciduous tree species possess a remarkable ability to thrive in arid environments while simultaneously showcasing resilience against the toxic effects of juglone. Their capacity for adaptation and hardiness make them an intriguing subject of study within the realm of botany.
Dogwood (Cornus alternifolia)
A notable characteristic of dogwoods is the explosion of vibrant flowers that adorn the trees during the spring season. The sheer abundance of blooms creates a breathtaking display that is hard to miss.
Rose of Sharon (Hibiscus syriacus)
Rose of Sharon, a member of the Hibiscus genus, is renowned for its extravagant blooms. These stunning flowers are characterized by their impressive size and vibrant color palette, showcasing an array of hues that captivate the senses.
American Holly (Ilex opaca)
The American holly (Ilex americana) is a hardy evergreen that offers vibrant red berries during the winter months. For added color and interest, consider planting this shrub near your black walnut trees. While it’s possible to plant them together, be mindful of their mature heights, as American hollies can grow quite tall and may overshadow your walnuts if planted too close.
Sumac (Rhus copallina)
While often mistaken for its more notorious cousin, poison sumac (Toxicodendron vernix), sumacs are actually a type of shrub or small tree. One of the plant’s most notable features is its edible fruit, which ripens in the autumn. While some people do cultivate sumacs for their culinary potential, many others appreciate them primarily for their ornamental value, enjoying their striking foliage and vibrant colors.
