What to Plant Under Black Walnut Tree: Tips on Choosing Appropriate Plants

Black walnut trees are prized for their hard, dark timber and nutritious nuts. However, as they grow, they release a chemical called juglone that may inhibit the growth of other plants around them. If you have a black walnut tree on your property, it is important to choose plants that can tolerate or resist juglone. In this article, we will share some tips on what to plant under a black walnut tree.

Understanding Juglone Toxicity

Juglone is a chemical compound that the black walnut tree produces to protect itself from pests and pathogens. The chemical is found in all parts of the tree, including the nuts, leaves, bark, and roots. When the leaves or nuts fall to the ground, they decompose and release juglone into the soil. The substance can remain in the soil for up to two years, inhibiting the growth of many plants.

Plants That Are Resistant to Juglone

Thankfully, there are many plants that are resistant to juglone and can grow under a black walnut tree. These plants have evolved to tolerate the chemical over time. Some of the plants that you can consider planting include:

Daylilies

Hostas

Astilbes

Ferns

Columbines

Hellebores

Wildflowers such as Jacob's ladder and Virginia bluebells

It's important to note that while these plants can tolerate juglone, they may not thrive as well under a black walnut tree as they would in another location. The soil under a black walnut tree is also usually drier and more alkaline, so you should choose plants that prefer these conditions.

Plants That Can Be Affected by Juglone

On the other hand, there are some plants that are sensitive to juglone and should not be planted near a black walnut tree. These plants may exhibit stunted growth, yellowing leaves, and eventual death. Some of the plants to avoid include:

Tomatoes

Peppers

Potatoes

Apples

Pears

Blueberries

Raspberries

If you have these plants on your property, you should plant them at least 50 feet away from a black walnut tree. This will prevent them from being affected by juglone.

Tips for Planting Under a Black Walnut Tree

Here are some tips to help you successfully plant under a black walnut tree:

Choose plants that are known to be resistant to juglone

Check the pH of the soil and choose plants that prefer alkaline soil

Plant in spring or fall when moisture levels are high

Add organic matter to the soil to improve its structure and fertility

Apply a layer of mulch to help retain moisture and prevent weed growth

Water regularly, especially during dry periods

By following these tips, you can create a beautiful and thriving garden under your black walnut tree. With careful planning, you can enjoy a diverse range of plants that can coexist with your black walnut tree without being affected by juglone.