Laidback Gardener Tip of the Day

What to Grow Under a Walnut Tree?

20150628Black walnuts (Juglans nigra), and, to a lesser degree, other species of walnut, produce a toxic substance called juglone from both their roots and leaves. Juglone is said to be allelopathic, that is to say, specifically toxic to other plants.

Walnuts use juglone as a defense mechanism: by eliminating competing plants, they can more easily dominate the sector and benefit from all the ressources: minerals, water, etc. Even their own nuts have trouble germinating in their root zone, ensuring the mother tree can grow without competition.

If you’re growing a walnut tree, or intend to grow one, don’t give up all hope of having a beautiful and productive garden at its base. There are still many plants that are juglone-resistant.

Here’s a list to get you started!

  • Astilbe (Astilbe spp.) zone 4
  • Bean (Phaseolus vulgaris) vegetable
  • Beet (Beta vulgaris) vegetable
  • Bellflower (Campanula spp) zones 3-7
  • Bergenia (Bergenia spp.) zone 3
  • Black raspberry (Rubus occidentalis) zone 4
  • Bleeding heart (Dicentra spp.) zone 3
  • Boston Ivy (Parthenocissus tricuspidata) zone 4b
  • Brunnera (Brunnera macrophylla) zone 3
  • Bugleweed (Ajuga reptans) zone 3
  • Burning bush (Euonymus alata) zone 5
  • China pink (Dianthus chinensis) annual or perennial (zone 4)
  • Chrysanthemum (Chrysanthemum x morifolium) zones 4-7
  • Cleome (Cleome hasslerana) annual
  • Climbing honeysuckle (Lonicera spp.) zone 3
  • Coleus (Plectranthus scutellarioides) annual
  • Columbine (Aquilegia spp.) zone 3
  • Coral Bells (Heuchera spp.) zone 3
  • Corn, maize (Zea mays) grain
  • Crocus (Crocus spp.) zone 3
  • Daffodil, jonquil (Narcissus spp.) zone 3
  • Daylily (Hemerocallis spp.) zone 3
  • Eastern hemlock (Tsuga canadensis) zone 4
  • Epimedium (Epimedium spp.) zone 3
  • Evening primrose (Oenothera spp) zone 4
  • February daphne (Daphne mezereum) zone 3
  • Flowering fern, royal fern (Osmunda spp.) zone 3
  • Forsythia (Forsythia spp.) zones 4-7
  • Four o’clock (Mirabilis jalapa) annual
  • Garden impatiens (Impatiens walleriana) annual
  • Garden phlox (Phlox paniculata) zone 3b
  • Goat’s beard (Aruncus dioicus) zone 3
  • Grape hyacinth (Muscari spp.) zone 3
  • Hardy geranium (Geranium spp.) zone 4
  • Hollyhock (Alcea rosea) zone 3
  • Horned pansy (Viola cornuta) zone 4
  • Hosta (Hosta spp.) zone 3
  • Hyacinth (Hyacinthus orientalis) zone 4
  • Iris (Iris spp.) zones 3-8
  • Japanese maple (Acer palmatum) zone 5b
  • Japanese pachysandra (Pachysandra terminalis) zone 4
  • Juniper (Juniperus spp.) zones 1-7
  • Lady’s mantle (Alchemilla mollis) zone 3
  • Lamb’s ear (Stachys byzantina) zone 3
  • Leopard’s bane (Doronicum spp.) zone 4
  • Ligularia (Ligularia spp.) zones 3-4
  • Lima bean (Phaseolus lunatus) vegetable
  • Lungwort (Pulmonaria spp.) zone 3
  • Male fern (Dryopteris filix-mas) zone 5
  • Meadowsweet, dropwort, queen-of-the-prairie (Filipendula spp.) zone 3
  • Monarda, bergamot (Monarda spp.) zone 3
  • Morning glory (Ipomoea nil) annual climber
  • Northern maidenhair fern (Adiantum pedatum) zone 3
  • Onion (Allium cepa) vegetable
  • Pansy (Viola x wittrockiana) annual
  • Parsnip (Pastinaca sativa) vegetable
  • Showy stonecrop (Hylotelephium spectabile, syn. Sedum spectabile) zone 3
  • Shrub rose (Rosa spp.) zones 3-7
  • Siberian squill (Scilla siberica) zone 2
  • Snowdrop (Galanthus spp.) zone 3
  • Solomon’s seal (Polygonatum spp.) zone 3
  • Spiderwort (Tradescantia x andersoniana) zone 4
  • Sweet woodruff (Galium odoratum) zone 3
  • Tiarella, foamflower (Tiarella spp.) zone 3
  • Toad lily (Tricyrtis spp.) zones 4-6
  • Tulip (Tulipa spp.) zone 4
  • Viburnum (Viburnum spp.) zones 2-8
  • Violet (Viola spp.) zones 2-8
  • Virginia creeper (Parthenocissus quinquefolia) zone 3
  • Wax begonia (Begonia x semperflorens-cultorum) annual

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

9 comments on “What to Grow Under a Walnut Tree?

  1. Is there a perennial that can survive under a sugar maple? I tried hosta. They lived but did not flourish. Thank you.

  2. Pingback: Yes, You Can Compost Black Walnut Leaves | Laidback Gardener

  3. Hazar Panc

    Thank you for sharing this . I would like to know the differences between this tree and this one: Chandler Walnut Tree

    • ‘Chandler’ is a selection of Persian walnut (Juglans regia), a different species from black walnut (J. nigra). It produces much less juglone and rarely causes problems… unless it has been grafted onto black walnut rootstock. You’d have to check that with the nursery that supplied the tree.

  4. Laura Harrison

    Do the zones in the list mean this plant can grow but ONLY in this zone?

  5. Why are there zones behind the names? Do these plants only grow next to BW in that zone?

    • The zones are hardiness zones. They show the coldest zone where the plant will grow. A zone 3 plant will grow where winters are severely cold, a zone 8 plant will only tolerate mild winter weather.

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