For quite some time I have been doing the trial and error method, as well as asking friends and neighbours what edibles will grow near black walnut trees. I also have several future posts about black walnut tolerant ornamental flowers.
Many thanks to gardening guru Sophia, friends in Seaforth, and neighbour Marilyn, amongst others for helping me build this list!
My back yard has Black Walnut trees in the SW, NW, and NE corners, with a non-fruiting mulberry and catalpa in the SE corner. I garden in sandy soil, and rarely water beyond settling in transplants, for all that my gardens are lush and colourful. No doubt some failures are due to drought conditions. Also some of the failures I ascribed to the black walnuts, turn out to be more about in-sufficient sunlight, than about the juglone that the black walnut puts out through it’s roots. Juglone is also present in all parts of the tree; the leaves, twigs, nuts and branch litter. Many sources say that a thorough fall cleanup can greatly reduce the concentration of juglone in the soil. However the juglone from the roots will persist in the soil for several years before dissipating, even after the tree is taken down. Composted black walnut leaves should not be used around non-black walnut tolerant plants.
For more basic information on Black Walnuts, I’ll direct you to : https://en.wikipedia.org/wiki/Juglans_nigra
I hope that search engines will lead people here and that comments will add to this list of what can be grown. All of the food plants listed below will only grow and/or fruit well with sufficient sunlight. The rule of thumb that I’ve seen that holds true here; is that foods grown for their roots or their shoots (leaves) will do ok in some shade, whereas fruits need considerably more sun.
My biggest experimental success was harvesting smaller yields of snap and snow peas over a much longer season than full sun gardeners, since the plants were kept cool by afternoon shade.
Herb & Vegetables:
Alliums – all members of the onion family: Chives, Garlic, Leeks, Onions
Beans: both pole and bush beans
Bee balm (tea)
Daikon – Japanese radish
Lemon Balm (tea)
Peas: Sugar, snap and snow peas
Shiso – Japanese “basil”
Squash – I had great success with Japanese ‘red kuri’ kabocha
Fruit: all of which need enough sun to fruit well
Apricot (all stone fruits)
Russian Olive (invasive)
Many edible ornamental flowers including:
Agastache licorice flower
Calendula (pot marigold)
Viola sp. Johnny-jump-ups, Pansies, Violets
Dead nettle (lamium)
BLACK WALNUT INTOLERANT EDIBLES
Asparagus (may grow beyond root edge)
Brassicas: bok choy, broccoli, brussel sprouts, cabbage, cauliflower, collard greens, kale, mustard greens, rapini, turnip
Grapes (Wild grape vines will grow, but no fruit)
Nightshades – eggplants, tomatoes (Marilyn was able to harvest tomatoes from indeterminate/vining tomatoes, every other person I spoke with had no luck with tomatoes), peppers, potatoes
Rhubarb – limped along, the same plant thrives now that it is well beyond the drip line
Which lead me to the following excerpted comment about permaculture methods for black walnuts:
Reply by Ezekiel Handsome-Lake on March 22, 2010 at 9:58am
In my experience Mulberry does phenominally next to black walnut, both red (native) and white (chinese) thrive and fruit normally as close as can be to a black walnut. Also, my reading leads me to believe that Mulberry will create a buffer in to soil inhibiting juglone from passing to plants on the other side of a Mulberry root zone my observations in the field support this. Also, most alleopathic plants are concerned with disabling competition (hence the lack of grass under black walnuts because they are both surface feeders.) Therefore, many plants, such as smallfruits, should not be affected by alleopathic chemicals produced by trees.
The guild in Gaia’s Garden was designed in AZ and therefore there is a difference in the character of their hackberry. Hacks in the SW USA are a shrub or small tree, whereas in the Midwest they almost always attain the height of a large tree (Hackberry seeds are an excellent late season sugar source for humans and wildlife.) Because of their larger size in the North (and the fact that they are also alleopaths,) they made compete pretty vigorously with a co-planted walnut.
As far as nightshade, i’ve heard peppers work fine but tomatoes i’ve heard both sides, some say they work some say they don’t.
Black Locust is a good native nitrogen fixer, is very hardy and attracts a million bees, a guild which centered a black walnut with a Black Locust (coppicable, and good fuel wood,) nurse and a circle of mulberry (mulberry can be pruned heavily to shape or keep low,) could probably grow quite a wider range of food than a Walnut with no buffer.