The common walnut (Juglans regia) is a large, long-lived tree that eventually reaches 15–25 m in height and width, so it needs a spacious garden and should be planted well away from buildings. Choose a grafted variety rather than a seedling: grafted trees start cropping in five to seven years and give more uniform nuts. Plant in autumn or spring in deep, fertile, well-drained soil (pH 6.5–7.5) in a sunny position. Walnuts leaf out late, often in May, so they escape most spring frosts, although very late frosts can still damage the flowers. The roots, leaves and husks release juglone, which suppresses the growth of many plants, including tomatoes and potatoes, so do not plan a vegetable bed beneath the canopy. Prune only in late summer, as trees cut in winter or spring bleed heavily. Harvest in September and October when the green husks split and the nuts fall; remove the husks promptly and dry the nuts in a single layer in an airy place before storing.