black walnut toxicity

[alice florida]

am searching for shrubs, perennials and annuals which will grow well under black walnuts

[opabinia51]

I have read that Walnut tree (in general) have leaves that contain toxins that inhibit the growth of other plants. I can't tell you the names of plants that grow under walnut trees but, I can say that your best bet is to rake the leaves up in the fall and dispose of them in some way.

Try reading this article:

https://www.extension.umn.edu/projects/yardandgarden/ygbriefs/h407blkwal-tox.html

[The Helpful Gardener]

Unfortuneately the leaves are not the issue; juglone is exuded from the roots of the tree as a chemical pre-emergent to assure it's progeny grow unchallenged by competition.

The list in the article is short, but it's the first I've seen that actually says there are resistant plants; I always figured juglone killed everything but walnuts...

Scott

[opabinia51]

Actually, the leaves also contain Juglone. I have read though, that when the leaves are composted that the Juglone breaks down. Though, I still won't put them in my compost.

[The Helpful Gardener]

Sorry for the bad news (and the bad pun to come), but this sounds like a tough nut to crack...(flame shield up...)

With the market for black walnut veneer in Japan being what it is, perhaps cutting it down and planting a friendlier tree could be not only garden beneficial, but profitable...

Scott

[rowena]

I also have heard all the stuff about black walnuts but really have had no problem gowing flowers and scrubs under my many BW trees. I have houseleek and daffodills also a Tattantian honeysuckle all growing under one of my BW's and they are doing great coming back every year with no ill effects. Have also had caladiums under one and they did ok also. I treat my trees same as any other when planting near them, my peony bed near one with no trouble also iris daylilies are near but not right against. I live in northcentral Arkansas if that helps. I say go for it you never know what might happen. Good luck

[The Helpful Gardener]

Sounds like Rowena has given you a list of great plants for underneath Juglans nigra. Interesting to note many were bulb types (might short circuit the need to extract a lot of nutrition from the soil and thus the juglone) adn Tartarian Honey suckle will grow anywhere; that's why it's a Federally listed invasive...(we don't recommend that one...) Irises also have a corm (much like a bulb) and peony roots are sort of tuberous...makes me wonder if it's the differing root structures that allow Rowena's plants to thrive there. Rowena, have you tried any fibrous type roots there?

Scott

[rowena]

I may have missed named my honeysuckle as the one I have has grown into quite a large bush or small tree and has given me no problem with being invasive. I also have sweetpeas under my trees. and the house leek I have is not a bulb type and it is growing close to the trunk of my tree and among the large roots sticking up out of the ground. My liliacs are also quite near the BW's(within the limb spread).The only thing I had to fail near the trees was some colus that I planted in the shade but it was on a spot of bare ground where a poison vine had been taken out.( I blamed the poison ivy for that) as everything else I have there is doing good. I have also grown dusty miller in a bed around my BW's

[tfoster]

If you have any suggestions for shrubs or groundcovers to plant around black walnuts, I would really appreciate the tips. I recently purchased my family's old homeplace in NC and there is a 100 year old black walnut in the front yard... no way am I cutting that down. The only things I remember growing around it as a child are a cherry tree, nandina bushes and a catawba tree. There is a lilac close by, but it has never done very well... stunted growth and poor flowering. Any experience with azaleas around a black walnut?