I've been offered black walnut planer shavings to mulch my vegetable beds AND some scrap black walnut lumber to build raised flower beds.
I know that planting under black walnut trees is a problem. But what specifically is the problem? The leaves? Something in the soil because of the walnuts themselves? All I can find on the net is don't plant under the trees... not WHY?
You're welcome. We have Black Walnut trees all around here. Many times the squirrels "hide" them in my planters and I have to dig out many newly sprouted little trees every year. But the nuts are good. :)
Black walnut is negatively alleopathic with some plants. Nightshades (potatoes, tomatoes, peppers, eggplant, etc) and Brassicas are said to be particularly susceptible to the chemical (5 hydroxy-1, 4-napthoquinone) released by the walnut. Other plants are more tolerant of the chemical, but in my experience most have some negative effects from black walnut.