Growing healthy plants near a walnut tree can certainly be very challenging. Even plants up to 75' away can be adversely affected. This is due to a toxic substance called juglone that is given off by the roots and leaves of walnut trees. Juglone acts a growth inhibitor, which in essence is nature's way of suppressing the competition in order to ensure its survival. The poisonous zone extends about 20 to 30 meters from the trunk of a walnut mature tree.
Certain plants are more sensitive to juglone than others.
Plants to avoid: (These plants are very sensitive to the effects of juglone and will not perform well near a walnut tree).
- White pine
Plants to try: (These plants are more juglone tolerant and can usually be safely planted near a walnut tree).
- Bleeding heart
- Bearded iris
- Japanese maple
- Solomon's seal
- Winged euonymus
- Woodland phlox
For those who wish to grow vegetables near a walnut tree try constructing raised beds and line them well to keep out walnut roots. Container gardening is also an excellent option.