When life hands you a black walnut, you have to make certain concessions in the garden. Black walnut roots produce juglone - and it is toxic to many plants. Not fun, when the main tree in your landscape is a walnut. But one can make-do. And so I must.
In the realm of permaculture, there are possibilities for cooperation and love under the canopy of the black walnut. It is called a guild and they are plants that work with the juglone and don't wither in its company.
My go-to book for permaculture ideas is Gaia's Garden by Tobey Hemenway. He suggests plants like mulberries, elderberries, currants and black raspberries (photo above from Wikimedia) in a walnut guild and that is the direction I am going this summer.
So - as of today, I have three elderberry plants and one black raspberry in the ground and I am hunting down currants and mulberries. I also just read somewhere that hollyhocks put up with the demands of the walnut- so those will go in this weekend as well - for height and color. Take that, juglone!