Walnut trees grow into stately, long-lived shade trees, but they come with a quirk few other trees share — their roots release a chemical that can stunt or kill certain nearby plants.
Black walnut in particular produces juglone, a natural compound toxic to tomatoes, peppers, and several other garden plants, so its placement relative to a vegetable garden matters more than for almost any other tree.
Walnut trees want full sun and deep, well-draining soil, and given their eventual size, they need a large planting site set well away from vegetable gardens, especially if planting black walnut. English walnut is somewhat less allelopathic and a gentler choice near other plantings.
Never compost black walnut leaves, roots, or hulls near a vegetable garden — the juglone they contain persists in soil and can suppress or kill sensitive plants for years.
