42 Plants That Die Near Black Walnut Trees / Juglone

It has been well documented for centuries that some plants either struggle to grow near Black Walnut Trees, or are outright poisoned by them [1]. The toxic chemical the possess is called Juglone. Some plants are either stunted, die, or can’t germinate near Juglone.

Knowing what plants will struggle near Black Walnut Trees is important so you don’t spend money landscaping with them, or waste time growing certain vegetables [2], only to have them perish [4], [5].

Based on dozens of Journal Articles and University Ag Extensions, I’ve compiled a comprehensive list of 42 flowers, trees, and vegetables that can’t grow near a Black Walnut Tree. They will struggle to grow, or die if planted within 20-25′ of the dripline of a Black Walnut Tree.

Why Does the Black Walnut Tree kill other plants?

The Black Walnut Tree secretes a chemical from it’s roots, fallen leaves, and husk of the black walnut known as Juglone. This chemical gives the Black Walnut Tree (Juglans nigra) an allelopathic effect [3], killing certain plants that are within it’s canopy [5].

What is Allelopathy?

Allelopathy is where a plant secretes a chemical that will inhibit the growth of surrounding plants. Allelopathy is a neat evolutionary characteristic that some plants use to reduce competition. Think about it, if a tree can kill all surrounding plants, then it gets all the sunlight and soil nutrients.

As with any evolutionary process, some plants have been documented to be tolerant of Juglone. These plants can grow near, or within the canopy of a Black Walnut Tree. You may be interested to read the 201 different species of plants that are Juglone tolerant, and can grow near Black Walnut Trees.

Vegetables, Flowers, and Trees that Should NOT be planted near Black Walnut Trees!

How long does Juglone poison stay in the soil after cutting down a Black Walnut Tree?

So, if you remove a Black Walnut Tree and want to start a garden, fear not! There are certain bacteria that can feed solely on Juglone [6], which is likely a large component of the variation.  So, the bacteria known as Pseudomonas putida J1 was found to to break down Juglone rapidly if soil was aerated.

So, if you cut down a Black Walnut Tree in your yard, you will likely be able to begin planting flowers / trees / shrubs after removing a tree. It will just take some time for the bacteria to break down the Juglone in the soil.

Learn More About Black Walnut Trees