Black Walnut Toxicity – Grow Juglone-Resistant Plants

Part of the fun or for some the frustration of gardening is overcoming challenges and one big challenge for many gardeners is planting under a black walnut tree.

All parts of the black walnut tree contain a toxic substance called juglone that can cause stunting, wilting and even death in susceptible plants.

One solution is to grow juglone-tolerant plants. Review lists of juglone susceptible and resistant plants prepared by several Universities. These lists are based on observations and by no means complete, but they do provide a good starting point. You can do the same by adding one or two plants you want to try that do not appear on any of these lists. If the plants thrive, you can add more. If they suffer you may want to add them to your “Do Not Plant” list and try something new.

Minimize your frustration by growing susceptible plants at least 50 feet away from your black walnut tree. The further you move away from the tree, the lesser the concentration of the toxic juglone.

A bit more information: Or create a juglone-free raised bed. Cover the soil and line the sides of the raised bed with water permeable weed barrier fabric. The fabric can help slow or prevent the invasion of black walnut roots into the raised bed garden. Cover the barrier as you fill the bed with fresh topsoil free of juglone. And if you decide to remove the tree, be patient. The juglone remains in the soil until the roots, nuts and leaves totally decompose.