WALNUT TOXICITYBlack walnut roots release a toxin called Juglose that prevents many plants from growing. Plants that are susceptible to the toxicity and usually die slowly (by gradually wilting) include:
Tomato Alfalfa Pear Blackberry Red Pine Blueberry Mountain Laurel Azaleas Rhododendron Potentilla White PineOther evergreens may be affected.
To avoid injury, susceptible plants should be place at least eight feet past the walnut tree's dripline.
Walnut sawdust or wood chips have been shown to affect plants in a similar
fashion and should not be used as a mulch around these plants.
PERENNIAL PLANTS NOT AFFECTED
The following is a list of herbaceous perennial plants that appear NOT affected by the toxicity relased by walnut roots.
Ajuga reptans (bugle weed) Monarda didyma (Bee balm) Alcea rosea (Hollyhock) Monarda fistulosa (Wild bergamot) Asarum europeaeum (European wild ginger) Oenothera frutcosa (Sundrops) Osmunda cinnamomea (Cinnamon fern) Astilbe Phlox paniculata (Summer phlox) Camnpanula latifolia (Bellflower)Polemonium reptans (Jacob's ladder) Chyrsanthemums Polygonatum commutatum (Great Doronicum (Leopard's bane) Solomon's Seal) Dryopteris cristata (Crested Wood fern)Primula X polyantha (Polyanthus Galium Galium odoratum (Sweet woodruff) Primrose) Geranium robertianum (herb Robert)Pulmonaria (Lungwort) Geranium sanguineum (Cranesbill)Sanguinaria canadensis (Bloodroot) Helianthus tuberosus (JerusalemSanguinaria canadaensis 'Multiplex' artichoke) (Double flowered bloodroot) Hemerocallis (Daylily) Sedum acre (Gold moss) Heuchera X brizoides ('Pluie de Feu'Sedum spectabile Coral Bells) Stachys byzantina (Lamb's Ear) Hieracium aurantiacum (Orange Tradescantia virginiana (Spiderwort) Hawkweed) Trillium cernuum (Nodding trillium) Hosta fortunei Trillium grandiflorum (White Wake- Hosta lancifolia Robin, Trillum) Hosta marginata Uvularia grandiflora (Big merrybells) Hydrophyllum virginianum (VirginiaViola canadensis (Canada Violet) waterleaf) Viola sororia (Woody blue violet) Iris sibirca (Siberian Iris)
ANNUALS NOT AFFECTEDThe following is a partial list of annual flowers that appear NOT affected by the toxicity released by walnut roots.
Begonia (fibrous rooted) Calendulas Morning Glory Horned Violet Pansy
TREES NOT AFFECTEDThe following is a partial list of trees that appear NOT affected by the toxicity released by walnut roots.
Acer palmatum (Japanese Maple) Acer plamatum 'Dissectum' (Cutleaf Japanese Maple) Catalpa bignonioides (Common Catalpa) Tsuga canadensis (Canadian hemlock)
VINES/SHRUBS NOT AFFECTEDThe following is a partial list of vines and shrubs that appear NOT affected by the toxicity released by walnut roots.
Clematis Daphne Forsythia Hibiscus Rose-of-Sharon Tartarian Honeysuckle Virginia Creeper Rhododendron Exbury hybrids
WEEDS NOT AFFECTEDThe following is a partial list of weeds that appear NOT affected by the toxicity released by walnut roots.
Glechoma hederacea (Ground Ivy, Creeping Charlie) Oxalis corniculata (Creeping sorrel) Stellaria media (Chickweed) Taraxacum officinale (Dandelion) Veronica filiformis (Veronica speedwill)
BULBS AND BULBOUS PLANTS NOT AFFECTED
The following is a list of bulbs and bulbous plants that appear NOT affected by the toxicity released by walnut roots.
Chionodoxa (Glory-of-the-snow) Crocus Endymion (Spanish Bluebells) Eranthis (Winter Aconite) Galanthus (Snowdrop) Hyacinths Muscari (Grape Hyacinths) Narcissus (Daffodils) Scilla (Blue Squill) Tulips
See also Walnuts section in Mulch
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