Wild Ones 2002 Archive

QUESTION #1: I am in need of information and/or experience with growing natives under mature black walnut trees. The 2 trees are on neighboring
property and edge the entire west side of my backyard. I am in zone 5. I have planted pawpaw and redbud under them. I need evergreens, small
trees and shrubs, vines and ground covers. Thank you

-- Linda Lawrence of Ann Arbor, MI

RESPONSES: I found a good article on this subject on Ketzel Levine's Talking Plants website; he has a show on NPR. The website is:
http://www.npr.org/programs/talkingplants/why/2002/walnutguide.html

It includes a list of plants tolerant of Black Walnut toxicity, although you
have to use common sense while selecting from the list. (He includes Tree of
Heaven, Ailanthus altissima!).

-- Susan Bryan of Ann Arbor, MI


I have researched this question quite a bit, and have found that
very few native species are affected by juglone. I have white cedars,
junipers, various dogwoods, hawthorne, sassafras, ninebark, and viburnums
growing under the walnuts. The only ones that seem to be affected are some
viburnum cultivars. I have also been advised to plant my hackberry tree as
far as possible from the walnuts. I talked with Mike and Greg at Native Plant
Nursery yesterday, and they can't think of any natives that have been hurt by
growing near black walnuts, except maybe columbines. I also have bluestem
goldenrod, false solomon's seal, marsh blazing star, virginia creeeper,
American bittersweet, virgin's bower, strawberries, and others that are
growing fine directly under the walnuts. My understanding is that juglone
is mostly detrimental to plants in the nightshade family. Here's a couple
links with more info: http://ohioline.osu.edu/hyg-fact/1000/1148.html, and
http://www.wvu.edu/~agexten/hortcult/fruits/blkwalnt.html. Good Luck!

-- Scott Joling of Ann Arbor, MI


Tree and Shrub Handbook from the Morton Arboretum has a section on Plants Tolerant of Black Walnut Toxicity. This book is pretty specific for plants that do well in the Chicago area, but I see you're in Michigan so most of them should work for you as well. The handbook is a looseleaf binder, and you can buy each section separately for $2, I think. If you visit their website, you can probably obtain it through the mail. Go to http://www.mortonarb.org/ I'll list some of their suggestions.

Evergreens:
Chinese juniper, Juniperis chinensis
Common juniper, Juniperis communis
Red cedar, Juniperis virginiana
Shingle oak, Quercus imbricaria
Arborvitae, Thuja spp.
Eastern Hemlock, Tsuga canadensis

Vines:
Dutchman's pipe, Aristolochia durior
Bittersweet, Celastrus spp. (be sure to get the American, not European!!)Clematis spp.
Honeysuckle vine, Lonicera spp.
Virginia creeper, Parthenocissus spp.
Greenbriar, Smilax spp.
Wild grape, Vitis spp.

There is a long list of trees -- I'll pick out a few of the smaller ones:
Japanese maple, Acer palmatum & cultivars
Serviceberry, Amelanchier spp.
Pawpaw, Asimina triloba
American hornbeam, Carpinus caroliniana
Witchhazel, Hamamelis spp.
American Plum, Prunus americana
Staghorn Sumac, Rhus typhina
Willow, Salix spp.
Sassafras, Sassafras albidum
Slippery Elm, Ulmus rubra

Shrubs -- again, I'm being selective because the list is long
Speckled Alder, Alnus rugosa
Hercules-club, Aralia spinosa
Spicebush, Lindera benzoin
New Jersey Tea, Ceanothus americanus
Fringe Tree, Chionanthus verginicus
Pagoda Dogwood, Cornus alternifolia
Silky dogwood, Cornus amomum
American Hazelnut, Corylus americana
Ninebark, Physocarpus opulifolius
Exbury Rhododendron
Fragrant Sumac, Rhus aromatica
Shining sumac, R. copallina
Smooth sumac, R. glabra
Currant, Ribes spp.
Wild Rose, Rosa spp.
Black Raspberry, Rubus occidentalis
Purple Raspberry, Rubus odoratus
Elderberry, Sambucus spp.
Maplelef Vibernum, V. acerfolium
Fragrant " V. carlesii & cultivars
Arrowwood " V. dentatum & cultivars
Blackhaw, V. prunifolium

There's a long list of perennials, spring wildflowers and bulbs. I'll list ones that are good groundcovers:Wild Ginger, Asarum spp.
Jacob's Ladder, Polemonium reptans
Solomon's seal, Polygonatum spp.
Violet, Viola spp.
Stonecrop, Sedum spp. (non-native)
Lady fern, Athyrium spp.
Rattlesnake fern, Botrychium spp.
Sweet Woodruff, Galim odoratum (non-native)
Lungwort, Pulmonaria spp. (non-native)
Sensitive Fern, Onoclea sensibilis
Cinnamon Fern, Osmunda cinnamomea
Christmas fern, Polystichum spp.

-- Pat Clancy of Lisle, IL

I found that onions grown underneath have a very sweet sense about them.

-- Sandy Justis of Elgin, IL

I have a list that was given me by Lodi Farms on Wagner south of Scio Church. I have planted wildflowers under my two mature black walnuts and up to the front of my house. Although hydrangeas are not supposed to thrive, so far the oakleaf that I planted last fall is doing fine, although it is a tiny bit outside the dripline. You might want to visit them and get this info, even though it will not cover native versus non-native species. So far, in the bed under the walnuts, I have pulmonaria, mertensia, brunera, dicentra (both kinds), wild celandine
poppy and anenome syvestris. Planted before my arrival two years ago, ferns
and tradescantia also have done well. Good luck with your new yard!

-- Jan Loveland in Chelsea, MI

I have Common Witchhazel, Hazelnut, Smooth Hydrangea, Spicebush, Prairie Rose, and Blackhaw plus typical savanna forbs and grasses growing under the canopy of my Black Walnut tree with no ill effects.

-- Pat Hill of Elgin, IL

Black walnut roots put out a strong herbicide. A healthy tree will have nothing growing under it. I am told that all growth will stop on the walnut until the offending plants are dead. I got this from a forester with the Wisconsin DNR when I started my Walnut grove (about 1500).

If someone is thinking about getting started with Native Black Walnuts, they
should be sure they have a very deep soil and subsoil. Some of mine are doing
well and some have just stopped growing because there is a rock ledge at about
5 feet. Another consideration is to mulch excessively (or use a preemergent
herbicide) for about five years. The trees will again put all their energy
into killing the competition rather than growing. Eventually they will become
a sort of a bush rather than a tree.

-- Pete Christianson of Larsen, WI

4-29-02

Under our walnut trees here in zone 6 (KY) we have jewelweed, American
germander, wild white bergamot, downy wood mint, stinging nettle
(immediately counteracted by jewelweed but probably not a great yard idea),
yellow wingstem, Canada rye, honewort, wild geranium, woodland sunflower,
most all the spring ephemeral woodland wildflowers and a few ferns. For a
residential setting I think wild ginger and ferns (possibly woodsia sp) with
a few flowers would be lovely. Jacob's Ladder is very nice. A field of
violets would also me nice (mix some white and yellows with the more common
purples).

From Louisville Area Wild Ones

QUESTION #1 ADDITIONAL RESPONSES: Black Walnuts

5-16-02

A comment re stinging nettle mentioned in an earlier e-mail. The young leaves of nettle are nutritious and delicious. Of course one needs to be very careful picking them but they have no sting when they are cooked.

-- Dorothy Frohn of Oshkosh, WI

5-16-02

I wanted to point out that walnuts contain a naturally occurring toxin that causes plants placed within their root system and canopy not to flourish. I would suspect native species to be affected as well. Following is an excerpt from the web site appended that supports this information. http://www.npr.org/programs/talkingplants/why/2002/walnutguide.html

Black walnut (Juglans nigra) is considered one of our most valuable, native hardwood lumber trees and is often used in large scale landscapes. However, in the smaller-scale home landscape, the leaves and fruits are considered by some to be a messy nuisance. Furthermore, while many plants can grow well in proximity to a black walnut, there are certain plant species whose growth is inhibited by this tree. The term "allopathy" refers to the relationship between plants in which one plant produces a substance that inhibits the growth of sensitive plants nearby.

Source of Toxicity - Black walnuts produce a chemical called juglone, which occurs naturally in all parts of the tree, especially in the buds, nut hulls and roots. The leaves and stems contain smaller quantities of juglone, which is leached into the soil after they fall. The highest concentration of juglone occurs in the soil directly under the tree's canopy, but highly sensitive plants may exhibit toxicity symptoms beyond the canopy-drip line. Because decaying roots can release juglone, toxicity may occur for several years after a tree has been removed.

-- Bob Resch of La Grange, IL


5-15-02

My walnut has killed off several things, but none of them native.

-- Tom Bispala of Germantown, WI

ADDITIONAL RESPONSES QUESTION #1: What native plants grow under Black Walnut trees?

6-19-02
I have tried to recreate an understory near a row of walnuts on our city property based on a list I believe came from our local extension services. The sassafras and paw paws are growing very slowly. The flowering dogwood, although planted 7 years ago has never flowered (I did not buy it in flower so maybe it's just a "bum" tree). The serviceberries are in decline, a few branches dying each season. Pagoda dogwood and red bud have seeded in but are not mature enough to flower yet. I also planted some evergreens for privacy: the hemlocks are very happy as is the Black Hills spruce (planted closer to the road for its salt tolerance). The ground layer, all planted, includes wild geranium, mountain mint, white snakeroot, violets, blue stem goldenrod, zig-zag goldenrod, black cohosh, false Solomon's seal and Virginia creeper.

-- Celia Larsen of Northville, MI

SUMMARIZING - below is a list of plants which grow under walnut trees:

Michigan:
pawpaw and redbud
white cedars,
junipers, various dogwoods, hawthorne, sassafras, ninebark, and viburnums
bluestem
goldenrod, false solomon's seal, marsh blazing star, virginia creeeper,
American bittersweet, virgin's bower, strawberries, and others that are

Pagoda dogwood and red bud have seeded in but are not mature enough to flower yet. I also planted some evergreens for privacy: the hemlocks are very happy as is the Black Hills spruce (planted closer to the road for its salt tolerance). The ground layer, all planted, includes wild geranium, mountain mint, white snakeroot, violets, blue stem goldenrod, zig-zag goldenrod, black cohosh, false Solomon's seal and Virginia creeper.

pulmonaria, mertensia, brunera, dicentra (both kinds), wild celandine
poppy and anenome syvestris.
ferns
and tradescantia

Illinois:
Evergreens:
Chinese juniper, Juniperis chinensis
Common juniper, Juniperis communis
Red cedar, Juniperis virginiana
Shingle oak, Quercus imbricaria
Arborvitae, Thuja spp.
Eastern Hemlock, Tsuga canadensis

Vines:
Dutchman's pipe, Aristolochia duriorBittersweet, Celastrus spp. (be sure to get the American, not European!!)
Clematis spp.
Honeysuckle vine, Lonicera spp.
Virginia creeper, Parthenocissus spp.
Greenbriar, Smilax spp.
Wild grape, Vitis spp.

There is a long list of trees -- I'll pick out a few of the smaller ones:
Japanese maple, Acer palmatum & cultivars
Serviceberry, Amelanchier spp.
Pawpaw, Asimina triloba
American hornbeam, Carpinus caroliniana
Witchhazel, Hamamelis spp.
American Plum, Prunus americana
Staghorn Sumac, Rhus typhina
Willow, Salix spp.
Sassafras, Sassafras albidum
Slippery Elm, Ulmus rubra

Shrubs -- again, I'm being selective because the list is long
Speckled Alder, Alnus rugosa
Hercules-club, Aralia spinosa
Spicebush, Lindera benzoin
New Jersey Tea, Ceanothus americanus
Fringe Tree, Chionanthus verginicus
Pagoda Dogwood, Cornus alternifolia
Silky dogwood, Cornus amomum
American Hazelnut, Corylus americana
Ninebark, Physocarpus opulifolius
Exbury Rhododendron
Fragrant Sumac, Rhus aromatica
Shining sumac, R. copallina
Smooth sumac, R. glabra
Currant, Ribes spp.
Wild Rose, Rosa spp.
Black Raspberry, Rubus occidentalis
Purple Raspberry, Rubus odoratus
Elderberry, Sambucus spp.
Maplelef Vibernum, V. acerfolium
Fragrant " V. carlesii & cultivars
Arrowwood " V. dentatum & cultivars
Blackhaw, V. prunifolium

There's a long list of perennials, spring wildflowers and bulbs. I'll list ones that are good groundcovers:
Wild Ginger, Asarum spp.
Jacob's Ladder, Polemonium reptans
Solomon's seal, Polygonatum spp.
Violet, Viola spp.
Stonecrop, Sedum spp. (non-native)
Lady fern, Athyrium spp.
Rattlesnake fern, Botrychium spp.
Sweet Woodruff, Galim odoratum (non-native)
Lungwort, Pulmonaria spp. (non-native)
Sensitive Fern, Onoclea sensibilis
Cinnamon Fern, Osmunda cinnamomea
Christmas fern, Polystichum spp.

Common Witchhazel, Hazelnut, Smooth Hydrangea, Spicebush, Prairie Rose, and Blackhaw plus typical savanna forbs and grasses

Kentucky:
jewelweed, American
germander, wild white bergamot, downy wood mint, stinging nettle
(immediately counteracted by jewelweed but probably not a great yard idea),
yellow wingstem, Canada rye, honewort, wild geranium, woodland sunflower,
most all the spring ephemeral woodland wildflowers and a few ferns.

Larsen, WI:

Black walnut roots put out a strong herbicide. A healthy tree will have nothing growing under it. I am told that all growth will stop on the walnut until the offending plants are dead. I got this from a forester with the Wisconsin DNR when I started my Walnut grove (about 1500).