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Plants for Under Black Walnut Trees
Note that while some of these might live, they might not thrive or grow as well as they would outside of the influence of the walnut.
Hormone Secretion
For the record, the reason that plants do not grow well under black walnut trees is the roots of the tree secrete a hormone juglone. The effect of the hormone will be felt by plants in the root zone of the tree.The root zone of the tree extends for a distance of twice the distance from the trunk to the drip line. So, in other words, if the distance from the trunk to the drip line (where the tree branches end) is 20 feet. The roots will extend approximately another twenty feet from the drip line. The effective area the tree roots will then secrete juglone is forty feet from the trunk. If the distance from the trunk to the drip line is 15 feet, then the secretion area is 30 feet from the trunk.
Hormone Breaks Down
This hormone is broken down by composting. When juglone is exposed to air, water and composting bacteria the toxic effect breaks down in two to four weeks. If youre not sure, try planting a tomato transplant in the compost. If juglone is present, the transplant will die within a few weeks.
Sawdust or chippings from the tree should not be used fresh around plants. It takes approximately six months for the juglone to disappear from wood chips and sawdust. Applying fresh chips would be like to trying to grow under black walnut trees.
Under Black Walnut Trees
Trees
Japanese Maples, Acer palmatum and its cultivars
Southern Catalpa, Catalpa bignonioides
Eastern Redbud, Cercis canadensis
Canadian Hemlock, Tsuga canadensis
Vines and Shrubs
Clematis 'Red Cardinal'
February Daphne, Daphne mezereum
Euonymus species
Weeping Forsythia, Forsythia suspensa
Rose of Sharon, Hibiscus syriacus
Tartarian Honeysuckle, Lonicera tatarica, and most other Lonicera species
Virginia Creeper, Parthenocissus quinquefolia
Pinxterbloom, Rhododendron periclymenoides 'Gibraltar' and 'Balzac', Rhododendron Exbury hybrids
Multiflora Rose, Rosa multiflora
Black Raspberry, Rubus occidentalis
Arborvitaes, Thuja species
Koreanspice Viburnum, Viburnum carlesii, and most other Viburnum species
Annuals
Pot-marigold, Calendula officinalis 'Nonstop'
Begonia, fibrous cultivars
Morning Glory, Ipomoea 'Heavenly Blue'
Pansy Viola
Zinnia species
Vegetables
Squashes
Melons
Beans
Carrots
Corn
Fruit Trees
Peach
Nectarine
Cherry
Plum
Pear-Pyrus species
Herbaceous Perennials
Bugleweed, Ajuga reptans
Hollyhock, Alcea rosea
American Wood Anemone, Anemone quinquefolia
Jack-in-the-Pulpit, Arisaema triphyllum
European Wild Ginger, Asarum europaeum
Astilbe species
Bellflower, Campanula latifolia
Chrysanthemum species (some)
Glory-of-the-Snow, Chionodoxa luciliae
Spring Beauty, Claytonia virginica
Crocus species
Dutchman's Breeches, Dicentra cucullaria
Leopard's-Bane, Doronicum species
Crested Wood Fern, Dryopteris cristata
Winter Aconite, Eranthis hyemalis
Snowdrop, Galanthus nivalis
Sweet Woodruff, Galium odoratum
Herb Robert, Geranium robertianum
Cranesbill, Geranium sanguineum
Grasses (most) Gramineae family
Jerusalem Artichoke, Helianthus tuberosus
Common Daylily, Hemerocallis 'Pluie de Feu'
Coral Bells, Heuchera x brizoides
Orange Hawkweed, Hieracium aurantiacum
Plantain-lily, Hosta fortunei 'Glauca'
Hosta lancifolia
Hosta marginata
Hosta undulata 'Variegata'
Siberian Iris, Iris sibirica
Balm, Monarda didyma
Wild Bergamot, M. fistulosa
Grape Hyacinth, Muscari botryoides
Sweet Cicely, Myrrhis odorata
Sundrops, Oenothera fruticosa
Senstitive Fern, Onoclea sensibilis
Cinnamon Fern, Osmunda cinnamomea
Peony, Paeonia species (some)
Summer Phlox, Phlox paniculata
Mayapple, Podophyllum peltatum
Jacob's-Ladder, Polemonium reptans
Great Solomon's-Seal, Polygonatum commutatum
Polyanthus Primrose, Primula x polyantha
Lungwort, Pulmonaria species
Bloodroot, Sanguinaria canadensis
Goldmoss Stonecrop, Sedum acre
Showy Sedum, Sedum spectabile
Lamb's-Ear, Stachys byzantina
Spiderwort, Tradescantia virginiana
Nodding Trillium, Trillium cernuum
White Wake-Robin, Trillium grandiflorum
Tulipa Darwin 'White Valcano' and 'Cum Laude,' Parrot 'Blue Parrot,' Greigii 'Toronto'
Canada Violet, Viola canadensis
Horned Violet, Viola cornuta
Woolly Blue Violet, Viola sororia
Plants with Extreme Sensitivity under black walnut.
These may not grow well even well outside the normal range. (triple the distance from trunk to drip line)
Herbaceous Perennials
Colorado Columbine, Aquilegia caerulea
Wild Columbine, Aquilegia canadensis
Asparagus, Asparagus offinalis
Chrysanthemum Chrysanthumum species (some)
Baptisia australis
Hydrangea species
Lilies, Lilium species (particularly the Asian hybrids)
Narcissus 'John Evelyn,' 'Unsurpassable' 'King Alfred' and 'Ice Follies'
Peonies, Paeonia species (some)
Rhubarb, Rheum rhabarbarum
Trees
Silver Maple, Acer saccharinum
European Alder, Alnus glutinosa
White Birches, Betula species
Northern Hackberry, Celtis occidentalis
Apples and Crabapples, Malus species
Norway Spruce, Picea abies
Mugo Pine, Pinus mugo
Red Pine, Pinus resinosa
Eastern White Pine, Pinus strobus
Basswood, Tilia heterophylla
Shrubs
Red Chokeberry, Aronia arbutifolia
Hydrangea species
Mountain Laurels, Kalmia species
Privet, Ligustrum species
Amur Honeysuckle, Lonicera maackii
Brush Cinquefoil, Potentilla species
Rhododendrons and Azaleas,
Blackberry, Rubus allegheniensis
Lilacs, Syringa species and cultivars
Yew, Taxus species
Blueberry, Vaccinium corymbosum
Viburnum plicatum tomentosum 'Mariesii'
Annuals and Vegetables Transplants
Cabbage, Brassica oleracea capitata
Peppers, Capsicum species (some)
Tomatoes, Lycopersicon esculentum
Flowering Tobacco, Nicotiana alata
Petunia species and cultivars
Eggplant, Solanum melongena
Potato, Solanum tuberosum
I hope this list helps you grow your garden under black walnut trees. It has been compiled from multiple sources and there may be some disagreement between them. Should you find a plant that will grow well under black walnut trees for you that is not listed here, I hope you'll email me and tell me about it so I can share that information with others.
Do you have a question about Plants for Under Black Walnut Trees?
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