Do black walnut hulls contain juglone or other growth inhibitors? My husband brought some home and I am afraid to put them in in my garden or anywhere I want things to grow until I checked to see if the hulls contain bad stuff.
Yes, they do. Even the leaves contain it, which is why you should'nt compost them. Plan your garden away from the trees.
I recently read that sycamore trees also contain substances that inhibit growth in other plants.