Walnut walnut Walnut is a long-lived, large nut tree valued for flavorful nuts, shade, and timber. English/Persian walnut (Juglans regia) is the main nut species in gardens; black walnut (J. nigra) and Manchurian walnut (J. mandshurica) are hardier but differ in nut and growth. Choose hardy cultivars for colder zones. Walnuts exude juglone, an allelopathic compound from roots, leaves, and husks that can inhibit sensitive plants—plan siting carefully. Requires space (8–12 m spread) and full sun. Catkins and female flowers are separate on the same tree and can be damaged by late spring frost; a compatible pollinizer improves set. Trees bear after 4–8 years from grafted plants (longer from seed). Growing conditions LightFull sun (6–8+ hours of direct light). Sheltered from cold spring winds if possible. Soil typeDeep, well-drained loam with good calcium and organic matter. Avoid waterlogging and very shallow, compacted soils. Water requirementModerate. Keep evenly moist during establishment (first 3–5 years). Deep, infrequent watering during dry spells; drought-tolerant once mature. Nutrient requirementLow to moderate. Light nitrogen in early spring on young trees; mature trees often need only compost/mulch. Back to plant list
