The Black Walnut or Juglans nigra is a relative of the Common Walnut or Juglans regia. It was introduced to Europe in 1629 where it is cultivated as an ornamental and, in many regions, it is grown industrially because of the high quality of its wood.
It is a deciduous tree that can reach up to 45 m in height, forming a wide and open crown. The trunk is straight and has a brown or almost black bark that is very furrowed. The leaves are composite, yellowish green and are arranged alternately. The male flowers are slow, and the female flowers appear in bunches of two to five, ripening in autumn until they form a greenish-brown semi-carious fruit with a corrugated nut inside.
A widespread species in North America, it is also widely grown in Southern Europe, Southern South America and East Asia.
Direct sowing in autumn/winter or prior to spring sowing, cold stratification of the seeds can be done for 3-4 months. Planting medium can be used for pots or garden soil mixed with planting medium if sowing is done directly in the garden. The substrate must be moist and not waterlogged until the seeds have germinated.