Don't Plant Other Plants under Walnut Trees

Walnut trees have long been known to be allelopathic, which means they release chemicals that can inhibit the growth of other plants. This phenomenon, known as allelopathy, can be a significant problem for gardeners who want to grow other plants under walnut trees. It is essential to understand why walnut trees are allelopathic and what plants are susceptible to their chemical compounds.

Why are Walnut Trees Allelopathic?

Walnut trees are allelopathic because they release a chemical called juglone. Juglone is a natural toxin that is created by the tree’s roots, leaves, and fruit. It is a potent compound that has been shown to inhibit the growth of a wide range of plants, including many common garden plants. Juglone can also persist in the soil for a long time, meaning that even after a walnut tree is removed, other plants may still struggle to grow in the area.

What Plants are Susceptible to Juglone?

Juglone is toxic to a wide range of plants, but some plants are more susceptible than others. Some of the most commonly affected plants include tomatoes, peppers, potatoes, eggplants, and blueberries. Other plants that are sensitive to juglone include blackberries, raspberries, strawberries, and many flowering perennials. If you want to plant other plants under a walnut tree, it is essential to choose species that are known to be tolerant of juglone.

Plants that are Tolerant of Juglone

Despite the challenges of growing other plants under walnut trees, some plants are known to be tolerant of juglone. Some of these plants include ferns, hostas, liriope, and wild ginger. Other options for plants that can grow under walnut trees include dogwoods, hydrangeas, and some ornamental grasses. It is essential to research which plants are best suited for your specific growing conditions, but choosing the right plants can help make your garden more successful.

How to Minimize the Effects of Juglone on Other Plants

If you want to plant other plants under a walnut tree, there are several steps you can take to minimize the effects of juglone. One way to reduce the impact of juglone is to plant in raised beds or containers. This approach can help keep your plants out of direct contact with the soil, which can reduce the impact of the toxin. Another option is to plant under deciduous trees, which can intercept and break down juglone before it reaches your plants. Adding organic matter to your soil can also help reduce the impact of juglone, as can regular deep watering.

Conclusion

Walnut trees are allelopathic, which means they release chemicals that can inhibit the growth of other plants. If you want to plant other plants under a walnut tree, it is essential to choose species that are known to be tolerant of juglone. Additionally, there are several steps you can take to minimize the impact of juglone, including planting in raised beds, planting under deciduous trees, adding organic matter to your soil, and regular deep watering. By understanding how juglone affects other plants and taking appropriate measures, you can successfully grow a range of plants under a walnut tree.