What grows under Black Walnut trees? Because Black Walnut (Juglans nigra) trees produce a toxic chemical called juglone (5 hydroxy-1,4- napthoquinone), often the typical non-native plants grown in typical yards do not do well. Many native species, however, have adapted.
The toxic chemical juglone occurs naturally in all parts of the Black Walnut tree – buds, leaves, nut hulls, stems and roots – and leaches into the soil as these parts of the tree fall and/or decay.
“Other trees closely related to black walnut — such as butternut, pecan, shagbark hickory and English walnut — also produce juglone, but at concentrations lower than black walnut. Rarely do these trees affect juglone-sensitive plants. (NPR)
During my tenure as Wild Ones Executive Director, the topic of discussion frequently was “what grows under black walnut trees” so I’ve kept a list of the variety of plants Wild Ones members from Northeastern and Midwestern USA have grown under and around Black Walnut trees.
Here’s the list of Native plants that grow under and nearby Black Walnut Trees:
Perennials:
American Germander (Teucrium canadense)
Bergamot (Monarda didyma)
Black Cohosh (Cimicifuga racemosa)
Bluestem Goldenrod (Solidago caesia)
Celandine poppy (Stylophorum diphyllum)
Downy Wood Mint (Blephilia ciliata)
Dutchman’s Breeches (Dicentra cucullaria)
False Solomon’s Seal (Maianthemum racemosum)
Honewort (Cryptotaenia canadensis)
Jacob’s Ladder (Polemonium reptans)
Jewelweed (Impatiens capensis)
Marsh Blazingstar (Liatris spicata)
Mountain Mint (Pycnanthemum virginianum)
Solomon’s Seal (Polygonatum spp)
spiderwort (Tradescantia spp)
violet (Viola spp)
Virginia Bluebells (Mertensia virginica)
White Snakeroot (Eupatorium rugosum)
Wild Bleeding Heart (Dicentra eximia)
Wild Strawberry (Fragaria virginiana)
Wild Geranium (Geranium maculatum)
Wild Ginger (Asarum caudatum)
Woodland Sunflower (Helianthus strumosus)
Yellow Wingstem (Verbesina alternifolia)
Zigzag Goldenrod (Solidago flexicaulis)
Grasses:
Big Bluestem (Andropogan gerardii)
Canada Wild Rye (Elymus canadensis)
Ferns:
Christmas Fern (Polystichum acrostichoides)
Cinnamon Fern (Osmunda cinnamomea)
Lady Fern (Athyrium filix-femina)
Rattlesnake Fern (Botrychium virginianum)
Sensitive Fern (Onoclea sensibilis)
woodsia (Woodsia spp)
Vines:
American Bittersweet (Celastrus scandens)
Dutchman’s Pipe (Aristolochia durior)
greenbriar (Smilax spp)
Honeysuckle Vine (Lonicera spp)
Virgin’s Bower (Clematis virginiana)
Virginia Creeper (Parthenocissus quinquefolia)
wild grape (Vitis spp)
Trees:
American Hornbeam (Carpinus caroliniana)
American Plum (Prunus americana)
Eastern Redbud (Cercis canadensis)
Eastern Hemlock (Tsuga canadensis)
Hawthorn (Crataegus monogyna)
Pagoda Dogwood (Cornus alternifolia)
Pawpaw (Asimina triloba)
Sassafras (Sassafras albidum)
Slippery Elm (Ulmus rubra)
Staghorn Sumac (Rhus typhina)
willow (Salix spp)
Shrubs:
American Hazelnut (Corylus americana)
Arrowwood Vibernum (Vibernum dentatum)
Black Raspberry (Rubus occidentalis)
Blackhaw (Viburnum prunifolium)
currant (Ribes spp)
Devil’s Walking Stick (Aralia spinosa)
elderberry (Sambucus spp)
Fragrant Sumac (Rhus aromatica)
Fringe Tree (Chionanthus verginicus)
Mapleleaf Vibernum (Vibernum acerfolium)
New Jersey Tea (Ceanothus americanus)
Ninebark (Physocarpus opulifolius)
Purple Raspberry (Rubus odoratus)
Rhododendron (Rhododendron spp)
Shining Sumac (Rhus copallina)
Silky Dogwood (Cornus amomum)
Smooth sumac (Rhus glabra)
Smooth Hydrangea (Hydrangea arborescens)
Speckled Alder (Alnus rugosa)
Spicebush (Lindera benzoin)
wild rose (Rosa spp)
Witchhazel (Hamamelis spp)
Evergreens:
arborvitae (Thuja spp)
Black Hills Spruce (Picea glauca)
Eastern White Cedar (Thuga occidentalis)
Eastern Hemlock (Tsuga canadensis)
Eastern Red Cedar (Juniperis virginiana)
juniper (Juniperus spp)
Shingle oak (Quercus imbricaria)
Plants that do not do as well:
Hackberry tree (Celtis occidientalis)
Serviceberry tree (Amelanchier spp)
Wild Columbine perennial (Aguilegia canadensis)
The Black Walnut is a tap root tree and thus does not have a massive horizontal root system like the typical maple, but the success of growing any of the plants listed above will depend upon the soil and the moisture conditions available to these plants. If you can add to this list, please let me know.
The Morton Aboretum has an extensive list of plants that grow under Black Walnut trees which includes non-natives.
Very interesting. I’ve printed out your list for future reference.
It’s good to hear from you, Holly. Have a wonderful holiday season!
What types of rhododendron did you have luck with? Every list I’ve seen shows rhododendron as extremely sensitive to juglone and my own failing Boule de Neige is actually what led me to discover juglone and it’s adverse effects in the first place. It seems many of the ericaceous shrubs are quite sensitive, as I am also beginning to see negative effects on my mountain laurels and Pieris japonica
Lauren — how many trees are there? Only one? — Donna
Can newly planted blue spruce trees be planted close by a mature black walnut tree? I have planted 3 spruces about 20 to 40 feet away and they did not live but about a year. Do you think it was the black walnut or something else entirely?
What climate/ecogregion did you plant them in, Ricki — Donna