By Erin Marissa Russell
If your property includes a black walnut tree, you’re likely familiar with black walnut toxicity and the difficulty of keeping plants near your black walnut tree alive. However, you may not be aware that some plants are not as susceptible to black walnut toxicity as others and can successfully be grown near or even right underneath a black walnut tree.
We’ve compiled plant lists containing various types of plants you can count on to flourish underneath black walnut trees, along with some details about each plant. But first, let’s take a look at why it’s so difficult for most plants to prosper when they grow too near to a black walnut tree.
Black Walnut Toxicity: Why do plants struggle near black walnut trees?
Every part of a black walnut tree contains a chemical called juglone, which is what makes the growth of other plants so difficult near a black walnut tree. The chemical juglone is at its highest concentrations in the black walnut roots, tree buds, and in the shells of the black walnuts themselves. Juglone is toxic to a number of other plant species because it inhibits their respiration, reducing the level of the energy that enables them to gather nutrients and ingest water.
As rain falls over the black walnut tree and down through the layers of soil and rock to join the groundwater underneath, it carries bits of juglone with it into the soil. However, juglone is not very water soluble, so it tends to stay in the soil surrounding a black walnut tree, which is why there seems to be a poor growth zone that extends out from the tree itself. (The soil holds the most juglone within the black walnut tree’s canopy dripline because of the root system as well as decaying leaves and walnut shells that fall there.)
Juglone in the soil is one reason why even chopping down a black walnut tree on your property will not put an end to the difficulty of growing plants where the tree once stood. Another reason is that the decaying black walnut tree roots will continue to release more juglone into the soil underground for many years after the tree has been cut down.
Plant life that is suffering from juglone toxicity can show symptoms in all parts of the plant manifesting as discolored leaves that turn yellow or brown, leaf shape distortion, overall decline of the plant’s health, stunted growth or failure to grow, and wilting foliage. When plants extremely sensitive to juglone are exposed to it, they can get sick and die within just a few days or weeks.
Plants with less extreme sensitivity could survive for a year and exhibit a much more gradual decline. That’s why if your property has a black walnut tree, it’s vital for you to know the juglone sensitivity of the plants you cultivate and any plants you’re considering adding to your collection. Unfortunately, once juglone damage occurs, there is no way to treat or reverse it.
With plants that are sensitive to the effects of juglone black walnut trees produce, experts recommend they be placed outside of the tree’s dripline, or at minimum, at a distance of 50 feet from the black walnut tree. The highest concentration of juglone will be within the dripline, but the tree’s roots (and the juglone’s effects) can stretch to a distance that equals the tree’s height.
Despite these drawbacks, there are plenty of juglone-resistant plants for gardeners to choose from that are either tolerant of juglone or immune to its effects. The following list contains plants you may want to choose to grow underneath or close to your black walnut tree.
49 Flowers for Planting Under a Black Walnut Tree
Anemone (Anemonastrum)
False Goat’s Beard (Astilbe)
Bee Balm (Monarda)
Birthroots (Trillium)
Black-Eyed Susan (Rudbeckia hirta)
Bleeding Heart (Lamprocapnos spectabilis)
Bugleherb (Ajuga reptans)
Common Bluebell (Hyacinthoides non-scripta)
Common Cinquefoil (Potentilla canadensis)
Common Evening Primrose (Oenothera biennis)
Common Fleabane (Erigeron)
Common Mallow (Malva neglecta )
Common Marigold / Pot Marigold / Scotch Marigold (Calendula officinalis)
Common Sneezeweed (Helenium)
Crocus
Daisy Fleabane (Erigeron anuus)
Darwin Tulip (Tulipa × gesneriana)
Daylily (Hemerocallis)
Dutchman’s Pipe Vine (Aristolochia)
Grape Hyacinth (Muscari armeniacum)
Hollyhocks (Alcea rosea)
Honeysuckle (Lonicera) —Certain varieties only
Garden Phlox (Phlox paniculata)
Geranium (Pelargonium)
Geum (Avens)
Greek Valerian / Jacob’s Ladder (Polemonium caeruleum)
Leather Flower (Clematis) [https://www.gardeningchannel.com/how-to-grow-propagate-clematis/]
Lily Turf (Liriope muscari)
Lungwort (Pulmonaria officinalis)
Mistflower (Conoclinium coelestinum)
Morning Glory (Ipomoea purpurea)
Obedience / Obedient Plant / False Dragonhead (Physostegia virginiana)
Ox-Eye Daisy / Dog Daisy (Leucanthemum vulgare)
Pansy (Violas)
Shasta Daisy (Leucanthemum × superbum)
Siberian Iris (Iris sibirica)
Siberian Squill (Scilla sibirica)
Shrubby St. John’s Wort (Hypericum prolificum)
Sweet Woodruff (Galium odoratum)
Tall Thimbleweed (Anemone virginiana)
Uniform Bellflower (Campanula carpatica ‘Uniform’)
Virginia Springbeauty (Claytonia virginica)
Wild Rose (Rosa acicularis)
Yarrow (Achillea millefolium)
26 Ornamental Plants That Will Succeed Under a Black Walnut Tree
Blue Fescue Grass (Festuca glauca)
Cat Grass/Cock’s Foot/Orchard Grass (Dactylis glomerata)
Common Sage (Salvia officinalis)
Coral Bells (Heuchera)
Greenbrier (Smilax spp.)
Hostas —Certain varieties only
Jack-in-the-pulpit (Arisaema triphyllum)
Kentucky Bluegrass (Poa pratensis)
Lamb’s Ear/Wooly Hedgenettle (Stachys byzantina)
Mayapple (Podophyllum Peltatum)
Oriental Bittersweet/Asian Bittersweet/Chinese Bittersweet (Celastrus orbiculatus)
Pawpaw (Asimina triloba)
Pussy Willow / Glaucous Willow (Salix discolor)
Pussytoes / Catsfoot / Everlasting / Ladies’ Tobacco (Antennaria plantaginifolia)
Sedge (Carex)
Solomon’s Seal, Variegated (Polygonatum odoratum var. pluriflorum)
Spiked Speedwell / Veronica (Veronica spicata)
Spiderwort (Tradescantia)
Stonecrops (Sedums)
Sunflower (Helianthus)
Timothy Grass (Phleum pratense)
Virginia Creeper (Parthenocissus quinquefolia)
Wheat (Triticum)
White Clover (Trifolium repens)
Wild Ginger (Asarum)
18 Fruit and Vegetable Plants That Will Flourish Under a Black Walnut Tree
Beans, including Lima Beans, Snap Beans, and Soybeans
Beets (Beta)
Black Raspberry (Rubus occidentalis)
Carrots (Daucus carota subsp. sativus)
Cauliflower (Brassica oleracea var. botrytis)
Cherries (Prunus avium)
Common Grape Vine/Wild Grape (Vitis vinifera)
Corn (Zea mays subsp. mays L.)
Garlic (Allium sativum)
Jerusalem Artichoke (Helianthus tuberosus)
Leeks (Allium ampeloprasum var. porrum)
Onions (Allium cepa)
Parsnip (Pastinaca sativa)
Parsley (Petroselinum crispum)
39 Shrubs and Trees to Grow Near a Black Walnut Tree
American Beech (Fagus grandifolia)
American Elm Tree (Ulmus americana)
Arborvitae Tree (Thuja)
Black Gum Tree/Sour Gum Tree/Tupelo (Nyssa sylvatica)
Black Locust Tree (Robinia pseudoacacia)
Blackhaw Viburnum (Viburnum prunifolium)
Canadian Hemlock Tree/Eastern Hemlock Tree (Tsuga canadensis)
Cigar Tree (Catalpa)
Corkscrew Willow Tree (Salix Matsudana
Currant Shrub (Ribes)
Eastern Redbud Tree (Cercis canadensis)
Flowering Dogwood (Cornus florida)
Forsythia Shrubs [https://www.gardeningchannel.com/how-to-grow-forsythia/]
Hackberry Tree (Celtis occidentalis)
Hawthorn Tree (Crataegus) [https://www.gardeningchannel.com/how-to-grow-hawthorn-trees/]
Hickory Tree (Carya)
Honey Locust Tree (Gleditsia triacanthos)
Linden Tree (Tilia)
Maple Tree (Acer)—Certain varieties only (including sugar maple, Japanese maple, and red maple)
Mohican Viburnum (Viburnum lantana ‘Mohican’)
Mulberry Tree (Morus)
Ninebark (Physocarpus)
Oak Tree (Quercus)
Ohio Buckeye (Aesculus glabra)
Pachysandra Shrub
Pagoda Dogwood (Cornus alternifolia)
Poplar Tree (Populus)
Red Cedar Tree / Eastern Red Cedar Tree / Virginian Juniper Tree (Juniperus virginiana)
Rose of Sharon / Common Hibiscus (Hibiscus syriacus)
Saskatoon/Serviceberry/Shadbush/Shadblow/Shadwood/Juneberry (Amelanchier)
Sassafras Tree (Sassafras albidum)
Smooth Hydrangea / Wild Hydrangea (Hydrangea arborescens)
Southern Catalpa (Catalpa bignonioides)
Spindle Tree / Burning-Bush / Strawberry-Bush / Wahoo / Wintercreeper (Euonymus)
Sumac (Rhus)
Sycamore Tree/Buttonwood Tree/Buttonball Tree (Platanus occidentalis)
Tulip Tree (Liriodendron)
Weeping Willow Tree (Salix babylonica)
Witch-Hazel Shrub (Hamamelis virginiana)
Yamabuki/Japanese Marigold Bush (Kerria)
A Few More Things You Should Know About Gardening Around a Black Walnut Tree …
Don’t compost any part of the black walnut tree. Don’t use any materials from the black walnut tree in compost, or you risk poisoning the soil where you spread the compost instead of enriching it. The juglone that makes a black walnut tree and the soil where one has grown so toxic to most other plants will still be present in the organic matter that is produced. This embargo on black walnut tree debris goes for the tree’s foliage (its leaves), bark, branches, twigs, walnuts, walnut shells, and the soil anywhere close to the tree.
Clean up after your black walnut tree to protect the rest of your garden. If you see black walnut seedlings pop up in a neighboring garden bed or peek out over the lawn, be sure to pull the baby black walnut trees up and discard them. Use a broom or rake to clean your property of all the whole walnuts, walnut shells, and leaves that your walnut tree drops about once a week, and dispose of what you find in the trash.
Even if you haven’t noticed any black walnut debris as you go about your days, do a walk about once a week, covering just the vicinity of your black walnut trees if the entire property will take too long to inspect weekly. It doesn’t take long for the presence of juglone to do serious damage to highly sensitive plants.Parts of the tree may have been carried to faraway parts of the yard by birds, squirrels, and other wildlife or knocked loose by a blustery wind or sudden storm, so you may not even know they’re on the ground until you look for them.
If your garden needs some extra help, try raised beds or container gardens and rich soil amendments. Choosing plants that tolerate juglone well is a giant step toward improving the overall health of your garden. But sometimes you just really want to nurture a plant that’s sensitive to juglone, or you’ve been experiencing trouble growing plants even outside the black walnut tree’s dripline. There are actions you can take to improve the soil your plants grow in and decrease the juglone it contains. Constructing raised beds will let you grow your plants without the tree’s root system sneaking in from underneath. It also helps to keep the ground near the black walnut tree well aerated, and use microbe-enhancing soil amendments like composted leaves or well-rotted manure.
Learn More About Juglone Tolerant Plants and Black Walnut Trees
https://www.canr.msu.edu/news/growing_vegetable_gardens_near_black_walnut_trees
https://www.dailyharvestdesigns.com/blog/tag/plants+tolerant+of+black+walnut+toxicity
http://www.ecosystemgardening.com/what-to-plant-under-black-walnut-trees.html
https://www.extension.iastate.edu/news/2005/jul/070701.htm
https://extension.umd.edu/learn/toxic-plant-profile-black-walnut
https://www.groworganic.com/blogs/articles/companion-plants-that-tolerate-black-walnut-tree-toxicity
https://homeguides.sfgate.com/can-fruit-trees-grow-next-black-walnuts-58099.html
https://joybileefarm.com/plants-will-grow-near-black-walnut-trees/
https://www.melindamyers.com/articles/gardening-beneath-a-black-walnut
http://www.murphysgardens.com/blackwalnuttolerantplants.html
http://www.omafra.gov.on.ca/english/crops/facts/info_walnut_toxicity.htm
https://www.provenwinners.com/learn/landscaping/curse-black-walnut
https://www.usperennials.com/perennials-by-collections/plants-tolerant-to-black-walnut/
Are gladiolus sensitive to black walnut trees? I’m in a zone 5 and pull the bulbs in fall for replanting.
Some tolerant plants are printed in red and some in black with no explanation.
Is there a reason or is the author color blind?
The red ones are links to those plants.
I was thinking of planting some Jerusalem Artichokes in a sunny space within the drip zone of a mature black walnut tree in my yard. My only concern is if the juglone toxin is absorbed into the tubers. I am allergic to nuts and wasn’t sure if those allergens would be present in the artichoke tubers I want to harvest because of their proximity to the tree. Thanks for any info you can supply.
The words in red are a “hyperlink” which means if you click on them, you will be directed to another website that tells you more about that specific plant. To get back to the original list, try your back arrow in the upper left of your screen or click on the tab to the left of the tab you have open now (tabs look like paper file folder tabs). 🙂
Do you know if thuja hedges grow well or don’t agree with black walnut trees?
There are three under a walnut tree (that’s a tree bearing fruit, i. e. walnuts) and they are dying. But on the other side there’s another black walnut tree (that one doesn’t have fruit but long red flowers) and there the hedge grows well.
Thank you for this extensive article on a difficult problem.
However, I would ask you to please never promote that highly invasive tree-killer vine:
Oriental Bittersweet/Asian Bittersweet/Chinese Bittersweet (Celastrus orbiculatus)
It’s listed as one of the top ten most invasive species in the north east, and it’s taking down thousands of trees, and very difficult to eradicate due to its extensive root system- requiring repeated herbicide treatments.
Rather promote native species that really need a boost- like the native American bittersweet vine, which is being out-competed by the oriental bittersweet
The PRISM network of New York is a good source of info on invasive species and native alternatives, and plants.usda.gov is a good quick reference source of checking the native (or non) status of each plant.
Hope this helps
What about Crepe myrtles ? I just planted 2.
I have Emerald Green Arborvitae and they have been growing, but when I bought the property it was empty except for a massive rose of sharon and very mature privet hedge that lined the property.
I have 3 Rhododendrons, various Maples, Cercis, Hdrangea, Hellebore, Azaleas, Sambucca, Pittosporum tenuifolium, Buxus, Westringia, Prunus lusitanica (Portuguese laurel), Pieris and possibly others growing directly under or beneath the canopy of the 85 yo inherited black walnut next to my house. All seem to be doing fine.