Introduction

Black walnut trees are native to North America and are commonly found in forests, parks, and residential landscapes. While they are prized for their valuable timber and flavorful nuts, they also have a unique trait that can make them a nuisance to gardeners and farmers alike. Black walnut trees release a chemical called juglone which is toxic to certain plants, making them unsuitable for planting in close proximity. In this article, we will explore what plants are sensitive to black walnut trees and why.

Plants Sensitive to Black Walnut Trees

There are certain plants that are highly sensitive to juglone and should not be planted near black walnut trees. Some of these plants include:

Azaleas

Rhododendrons

Mountain laurel

Hemlock

Redbud

Hydrangea

Lilacs

Apples

Tomatoes

Peppers

Potatoes

Eggplants

Blackberries

Raspberries

Why are These Plants Sensitive to Black Walnut Trees?

The reason why these plants are sensitive to black walnut trees is due to the chemical juglone. Juglone is naturally released by the tree and can be found in the leaves, bark, roots, and nut husks. When juglone is released into the soil, it can inhibit the growth of nearby plants. The severity of the toxicity depends on the concentration of juglone in the soil and the sensitivity of the plant. Some plants can tolerate low levels of juglone while others cannot.

How to Deal with Black Walnut Trees

If you have black walnut trees on your property, there are a few things you can do to minimize the negative impact on nearby plants:

Plant sensitive plants outside the root zone of the tree, which can extend up to 80 feet from the tree.

Use raised beds or containers for planting sensitive plants.

Test the soil for the presence of juglone before planting sensitive plants.

Prune back the branches of the tree to reduce the amount of shade and juglone-producing leaves that fall on the ground.

Remove fallen leaves and nuts to prevent the release of juglone into the soil.

If possible, consider removing the tree altogether or transplanting it to a location where it won't impact sensitive plants.

Conclusion

Black walnut trees are beautiful trees that provide valuable timber and delicious nuts, but they can also be a nuisance to gardeners and landscapers due to the release of juglone. Certain plants are highly sensitive to juglone and should not be planted near black walnut trees. If you have black walnut trees on your property, there are steps you can take to minimize the negative impact on nearby plants. By understanding what plants are sensitive to black walnut trees and why, you can make informed decisions when planning your garden or landscape.