Black Walnuts Tree - Black Walnuts are large shade trees that produce green large green nuts with a black core. Every part of a black walnut can release Juglan, a toxic chemical for many plants killing off many species around them. It is the way that Black Walnut Trees make space for their seeds to sow.
There are many plants that are Juglan tolerant but keep in mind, there's more to face under a walnut than the juglan. Their roots are vast, at least winder than the canpopy. They are supporting a large tree to they are water hogs and tend to deplete the moisture quite quickly. Due to its large nature, shade is also a big factor. Black Walnuts are not perfect but they are beautiful, well established trees that are strong and provide fruit and shelter for wildlife.
We do have a list of of plants available that are Juglan tolerant.
You are not the first gardener to come across a Black Walnut
Here is a list of some of the tips and tricks we have shared or learned from fellow gardeners that we recommend you try.
If you don't have sun and struggle with the moisture, consider using the space to create organization for your garden or back yard. a garden shed stays cool in the shade!
Get more light shinning through. Trim it up a bit to allow more sun to come in below it. It will look tidier too.
Do you really want annual under it? Buy some bags of potting mix and lay them under the tree where you want to plant. Cut the top out and poke some holes through the bottom for drainage and plant. After you plant, cover with a thick layer of mulch and no one will know the bag is there.
If you get enough sun you can build raised garden beds below it. Make sure decaying leaves and walnuts are always removed from the bed and line base with landscape fabric to create separation.
Most Hostas and English Ivy and thrive. This can create a beautiful shady escape for a hammock.