Walnut

Juglans nigra and Juglans regia
Family: Juglandaceae

Walnuts are large, deciduous trees producing edible nuts. The ball-shaped fruits are smooth and green and contain the nuts, which have dark brown, generally thin, furrowed shells. Walnuts are eaten raw or used in confectionery and cakes, and are delicious served with blue cheese or goat's cheese. Immature nuts can be pickled or candied. Some species of walnut are grown commercially for their beautiful timber.

Species

Juglans nigra, black walnut or American walnut, zone 4, grows to 30 m (100 ft) in its native territory, but very much smaller in cultivation. Like J. regia, this species has edible nuts. The fine timber of this species is used in furniture-making. Walnuts are slow growing but handsome trees.

J. regia, English or Persian walnut, zone 5, is a deciduous tree, 30 m (100 ft) high, with oblong leaflets, to 15 cm (6 in) in length, and pendulous clusters of small flowers borne on the previous year's wood. There are many fruiting cultivars available, such as 'Concorde', 'Eureka', 'Franquette' and 'Payne', but choose to suit your climate.

Cultivation

Trees should be planted in winter, while dormant. They should be placed no less than S m (16 ft), and preferably 7 m (23 ft), from other trees. They need deep, friable, well-drained soil and a plentiful supply of water during the growing season, either from deep, subsoil moisture or from regular irrigation. Feed trees in early spring with complete plant food. Pruning, if required, must be done during winter dormancy. Little pruning is generally needed except to train trees to a single main trunk, or to raise the crown by removing some of the lower branches. As trees grow and begin cropping, it is desirable to have a clear trunk to a height of at least 1.5 to 2 m (5-6 ft), to allow access to nuts as they autumn. Walnuts can be grown from seed, but the quality of trees will be variable. To maintain good strains, trees are budded or grafted onto seedling understocks.