Wild Ones   Wild Ones Archive 2002, Jun 01:  
  Ques#1: Growing under walnut  

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).
Next (Jun 02):
Ques#2: Natural landscaping over septic tank



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