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Report: Black Walnut Rose Plantings

Posted by Hawkeye_Belle Z6-PA (My Page) on
Fri, Jun 27, 03 at 10:43

Some months ago there was interest in what roses might grow beneath black walnut trees. People on the rose forum reported that hybrid musk roses were tolerant of the juglone toxin emitted by the Black Walnut Trees. Since I am surrounded by Black Walnuts (9) and love roses, I took the challenge and planted several roses. I already knew that Rugosa Roses are tolerant as I have these growing near one of the monsters. Also, multiflora roses are reported to be tolerant, and I have observed this in my part of the country, Pennsylvania. Therefore, I have also planted three multiflora hybrids, Paul's Himalayian Musk, Russelliana (Russell's Cottage Rose) and Veilchenblau. These were planted last spring and fall.

The hybrid musks planted this spring are:
Sky rocket, Daybreak, Bouquet Parfait, Prosperity, Lavender Lassie, Erfurt, Ballerina, Penelope.

One rugosa sucker from my rugosa rose bed was also transplanted here: Martin Forbisher.

These roses were planted in amended soil about 4 to 6 feet from the trunk of 2 very mature BW trees. Ones planted this spring were mainly own root roses, others are on multiflora root stock. The new babies did not receive any fertilizer until about two weeks ago. Others received spring fertilizer and again about two weeks ago. The fertilizer consisted of compost, holly tone and alfalfa meal. They are sprayed about every 14 days with the Cornell Formula (mainly horticultural oil and baking soda) to control pests and diseases. Here are the results:

None of the roses have croked. All are leafed out and some are blooming. Only two that arrived with bad cases of black spot are showing very minor infestions of black spot. The best performer so far is Erfurt with the most blooms, healthest leaves and most growth (although Penelope is quickly catching up). Veilchenblau is showing stress on the tips of several canes. I prune these back to healthy wood. She is blooming well on all unaffected canes and continues to grow

One hybrid musk (Andenken an Alma de l'Aigle) was planted in a "safe zone" at least 75 feet from any black walnut tree. It was a two year own root-most were one year own roots- and it looks no healthier, nor has it bloomed more. It has some black spot on its lower leaves.

This, of course, is just the beginning. Sometimes it takes several years for a plant to show the signs of juglone toxicity. So far, so good.

I have other plants as companions scattered about, but these all appear on one list or another for tolerance to juglone.

I hope some of you have found this interesting.

Follow-Up Postings:

RE: Report: Black Walnut Rose Plantings

I for one found it interesting. Here's a followup question: the area under my black walnut is in deep shade---are your roses are getting at least partial sun?

RE: Report: Black Walnut Rose Plantings

Thank you for expressing your interest. I didn't think anyone would notice.

Yes they are all getting at least 4 hours full sun per day which is OK for hybrid musk roses. Some are getting more.
The trees or on the Northeast side of my house, so the sun comes up behind them and sets in front of them. I also planted them far enough away from the trunk and at the edge of the tree drip line. So, they get dappled shade most of the rest of the day.

Do you have this issue (juglone toxin) to deal with in Portland? I thought Black Walnut's were mostly an east coast plague.

RE: Report: Black Walnut Rose Plantings

Black walnuts aren't native here, but were planted in abundance by early settlers. There is a related species that is native to Southern California---California black walnut---but what we have is the eastern variety.

I haven't yet been bothered by the juglone effect, perhaps because I'm too new to gardening to discern it. I know a lot of plants aren't bothered, and I have several growing contentedly under my own black walnut: bamboo, azalea, rhododendron, blue star creeper, forsythia, sweet woodruff. For me, my black walnut presents more or less the same problems of any large tree: shade, and competition from tree roots.

I'm actually fond of my tree--it's very useful at shading my house from the summer sun, and it reminds me of Tennessee where I grew up. It also supports a small colony of squirrels, and our racoons sometimes hang out in its branches.

RE: Report: Black Walnut Rose Plantings

Forsythia and Sweet Woodruff are both on the lists of tolerant plants. Azaleas and Rhodos are extremely sensitive to the toxin. There are two Azaleas consistantly listed as tolerant - Exbury Hybrids, Gibraltar and Balzac. One other that is sometimes listed is the pinxterbloom azalea.
I cannot tell you how many azaleas I lost before I discovered this problem. And eventhough I moved several to a "safe zone", I still lost them. Squirrels love to plant walnuts!
To be perfectly honest, I hate these trees. They make beautiful furniture and should be farmed by the acre well away from the home landscape. I, however, am surrounded by them, both on my property and my surrounding neighbors' properties. There is no other solution but to fight!

I suspect there may be other Exbury Hybrids that may grow and I intend to try some. Do you know what variety you have? Are they evergreen or deciduous? Exburys are the latter.

RE: Report: Black Walnut Rose Plantings

The azalea I have that thrives under my black walnut is evergreen, unless my memory is playing tricks on me. I'll make a point to watch it this winter.

RE: Report: Black Walnut Rose Plantings

Hawkeye Belle -- keep the reports coming! I'll be watching with great interest!

RE: Report: Black Walnut Rose Plantings

Hellebores, deutzia, phlox, rubeckia, heliopsis, yucca, cornus florida and leatherleaf viburnums are all thriving in the root area of my black walnut. I too loathe this tree except for the fabulous winter shape it makes aginst the sky. Like ink blown by a straw.

RE: Report: Black Walnut Rose Plantings

Laboopsie, Deutia and Hellebores are new listings to me. Thanks for the info. I am doing a new planting under two more trees that are in shade most of the day. I'll try the Hellebores there.

Always looking for plant information around these trees.

RE: Report: Black Walnut Rose Plantings

Hawkeye Belle, how are your plants doing now?
I have the same problem and need to find some thing that will perform a little better.

RE: Report: Black Walnut Rose Plantings

All are doing well, so far. The hybrid musk roses all came back and most have buds. Penelope was pruned to the ground due to die back but she is located in a vulnerable position where the winter wind gets her.
I've recently transplanted and planted the following:
2 oak leaf hydrangea, 2 purple leaf plums, 1 Japanese Maple (on partially leafed out-may have been damaged when moved) 2 dwarf forsythia new starts, several pylox, bergenia, hostas, astilbe, geranium,gallium, forget me nots, foam flower, spider wart, ligularia, lamium, ajuga keria hydrangea aboracens. Everything looks ok so far.
The roses do not seem as vigorous as in other locations, but they are healthy and budded.
Thank you for asking!

RE: Report: Black Walnut Rose Plantings

Has anyone had luck with hydrangeas under black walnut trees? I bought some specifically for planting under the row of walnut trees that grows along my driveway, but now I'm not sure what to do. There are lists all over the internet that separate those plants which will tolerate black walnut trees in close proximity and those that will not. Hydrangeas are showing up on both lists. How frustrating.

I have already lost a clematis and some lavendar plants this year. It's my first year at this new house, so I'm blaming the loss on the walnut trees. I don't want to take a chance on losing the hydrangeas as well.

Can anyone comment?

RE: Report: Black Walnut Rose Plantings

I have hydrangea macrophilia (sp?) aka Big Leaf Hydrangea growing within the root zone of my black walnuts and they are doing just fine. I am experimenting with Oak Leaf Hydrangea but it is too early to tell.
Go for it with the big leaf hydrangea. Hold off on the others unless you are willing to lose. Live and learn.

RE: Report: Black Walnut Rose Plantings

Thanks Hawkeye! I think I'll give it a try!

RE: Report: Black Walnut Rose Plantings

Hawkeye Belle, I think I told you on another thread that I was following your example and trying out some roses with multiflora ancestry under my own black walnut trees here in California. After about three months I can report healthy, even vigorous growth on the following roses planted in the root zone of my four trees.

Blue Magenta
Rose-Marie Viaud
Rambling Rector
Ghislaine de Feligonde
Treasure Trove
The Garland
Bobbie James

Most of these are once bloomers, so I won't know if they bloom properly for at least a year. Given that they are all ramblers or climbers, it may take a couple of years.


RE: Report: Black Walnut Rose Plantings

That is great news Paula. The only one I have is Veilchenblau. I had to move it because of disease. I don't think it got enough sun. It is still within the root zone of the BW and doing fine.

I was wondering about GdF. Such a beautiful rose. Thinking about getting this one. Does your rebloom? No matter; I like her anyway.

Yes, you are right about the length of time. My Paul's HM took three years before I got a decent bloom I think they need to stretch out first. Veil would have given a decent bloom this year but the rabbits did a number on her over the winter.

Thanks for this info.

RE: Report: Black Walnut Rose Plantings

I have several black walnut trees on the property that affect my gardening. Before I knew better I tried to grow tomatoes nearby! I finally dug them up to see what the problem was. The roots of the healthy tomato plant didn't have walnut roots in the soil below. The tomato plants growing over walnut roots were sickly in proportion to the mass of walnut roots below. When I spaded up the problem area I found it easy to recognize walnut roots by their strong distinctive odor. I had read that the roots stopped at the tree's dripline, but I have found them far out beyond that. Now, when I dig I smell every root I find and make a mental map. For two years I watered the tomatoes that thrived and skipped the sickly ones. Eventually the walnut roots grew into the soil with more moisture and I moved my tomato garden. Other plants, like a Niko Blue Hydranga have survived and even grown a little but have never bloomed. So, I judge that susceptability to Juglan Poisening varies not only from spcies to species but other factors as well. In fact, some plants (Kentucky Bluegrass, Eastern Hemlock) apparently thrive especially well on juglans. I wish I had a list of those that thrive, those that merely hang on, and those that die right away! Interesting plants cost too much (time especially) to test one by one, one year each, under a walnut tree. I'd also like to figure out what influences the direction the tree roots grow since they all seem to grow on hillsides. And, how deep do they grow? Can I put shallow rooted plants under walnut trees?
Any answers from your experience would be so very, very welcome! For example, Hellebores don't seem to be on any list I know about. can they thrive with juglans? I didn't start this thread, but my email address is "

RE: Report: Black Walnut Rose Plantings

There are many lists. I've give you a link to one. If you want more info. do a google search on Juglon Toxin or Black Walnut Poisen.
I have a Niko Blue thriving. Check out your plant and see if there is another reason it did not bloom. When did you prune it?
At first, I had a tendancy to blame all my failures on the BW tree. Now, I've just learned how to cope with it.

Tomatoe plants are the test for juglon infected soil. I am surrounded by 9 trees. Yet, there is a tomato volunteer in the center of one of my borders. I know that soil is juglon free.

Good luck!

Here is a link that might be useful: Landscape Juglone Tolerant Plants

RE: Ivy under black walnuts

I live in a windy area and I believe I have California Black Walnut trees. Until I found this site, I thought the only plant that would grow under black walnut was ivy. Good to know that there are other plants as well. Any suggestions for plants that can grow under the black walnut as well as in a windy area?

RE: Report: Black Walnut Rose Plantings

Organic joans, Try hostas, astilbes, some ferns like cinnamon ferns, day lilies, monada, spider warts, shasta daisies, siberian iris, toad lilies, aguga, kerria japonica and the aboracens hydrangea, Annabelle. Keep them well watered as the soil beneath any tree is often very dry.

Hope this helps.

RE: Report: Black Walnut Rose Plantings

Trying to cross-index for juglone resistance and resistance to deer and rabbits..doesn't leave much besides lambs ears,poison ivy and garlic chives.
The Dahoon holly I carefully planted away from the root zone in soil 3 feet above the level of the soil where the BW is located and now, three years later, the dahoon is showing tip leaf yellowing.
For all I know, there might have been a BW cut down when the lot was cleared below the dahoon location or the squirrels may be burying the nuts there.
It's very frustrating.

A question..I notice that the BW trunk and branches get almost black in rainy weather and now I note three or four with similar darkness in the other parts of the forest close to the yard.
Cutting these down and killing the roots is in the plan. Will I ever be able to plant at will or is removing all the roots necessary?

RE: Report: Black Walnut Rose Plantings

I'm new to this BW intolerant plant info. Planted to white hydrangeas two yrs ago. They died. This forum is so helpful. I will now try big leaf hydrangea. I hope it comes in white and is similar to the mop heads I planted. So far the cone flowers are ok, not thriving. I'll do a better job of checking the varieties on my plants. Also my forsythia is thriving along with the dayliies, bearded iris, pachysandra.

This post was edited by Diana195011 on Mon, Jul 21, 14 at 12:36

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