Black Walnut Information

Black walnut trees produce a chemical called juglone that inhibits the growth of neighboring plants.  It is a means of eliminating competition, referred to as allelopathy. The following list contains plants that show resistance to this chemical:

Perennials:

Ajuga reptans     Bugleweed

Alcea rosea    Hollyhock

Astilbe spp.     False Spirea

Athyrium spp.   Fern

Campanula carpatica   Bellflower

Chelone spp. Turtlehead

Dendranthemum spp.   Hardy Mum

Dicentra spectabilis   Bleeding Heart

Doronicum spp.   Leopard's Bane

Galium odoratum  Sweet Woodruff

Geranium sanquineum  Cranesbill

Hemerocallis spp.   Common Daylily

Hosta spp.      Plantain Lily

Iris siberica     Siberian Iris

Monarda didyma   Beebalm

Oenothera fruticosa      Sundrops

Osmunda cinnamomea   Cinnamon Fern

Phlox paniculata  Garden Phlox

Polemonium reptans    Jacob's Ladder

Polygonatum spp. Solomon's Seal

Pulmonaria spp. Lungwort

Sedum spectabile   Stonecrop

Stachys byzantina      Lamb's Ear

Tradescantia vir.    Spiderwort

Vinca minor     Periwinkle

Trees & Shrubs:

Acer palmatum     Japanese Maple

Acer saccharum     Sugar Maple

Betula nigra 'Heritage'    Riverbirch

Cercis canadensis      Redbud

Gleditsia triacanthos     Honey Locust

Halesia carolina    Carolina Silverbell

Hibiscus syriacus  Rose of Sharon

Ilex opaca    American Holly

Kerria japonica     Kerria

Liquidambar styr. Sweetgum

Philadelphus cor. Mock Orange

Prunus cistena      Purpleleaf Plum

Pyrus calleryana   Ornamental Pear

Quercus rubra     Northern Red Oak

Viburnum carlesii Koreanspice Viburnum

Susceptible Plants 

Sources