Which Vegetables Can Be Planted Near a Black Walnut Tree?
- Black walnut trees contain a chemical called jugalone that kills other plants near it. This process is called allelopathy, where one species of plant produces a toxic substance that reduces competition by other plants. While jugalone is toxic to most vegetable plants, some vegetables grow near black walnut trees.
- Lima beans and other snap beans are not sensitive to jugalone and can be planted near back walnut trees. However, beans require full sun or limited shade to grow and will not so well if planted directly under the tree. Black walnuts have a large canopy with deep shade directly beneath, but beans can be planted near the tree with no harmful affects.
- Corn is another vegetable that grows near a black walnut tree. Corn requires full sunlight to produce well, so it should not be planted directly beneath the tree. Corn requires high levels of nitrogen as well as potassium and phosphorus. Be careful when fertilizing the corn that the black walnut does not receive too much nitrogen because large amounts are not necessary to adult walnut trees.
- Plants in the allium family, including onions and garlic, can be planted near black walnut trees. Onions and garlic thrive in full sun, but can survive in partial shade so they can be planted closer to the trunk of the tree than other vegetables. Both garlic and onions require fertile, loamy soil and mild fertilization. The decomposed leaves of any tree can increase soil acidity and onions and garlic prefer a slightly acid soil with a pH of 6.0 to 6.5 so allowing the leaves to improve the soil will benefit the alliums.
