Family: Juglandaceae
Scientific name: Juglans nigra
Common name: Black walnut
Origin: United States

Black walnuts have a particular aromatic flavour which is very different from the common walnut. Black walnuts are much rarer in use, because the thick husk makes them very difficult to open. The nuts are often too big or too resistant for a nutcracker, and a hammer or vise would be needed to crack it. Before opening, the nuts should be dried in the sun. And when one manages to open the nut, it is a delicious nut which can be eaten directly or added as an ingredient to various dishes.  
The species originates in the eastern United States, where the trees can grow as big as 30 meters, often near riverbeds. The black walnut grows much faster than the common walnut, and can give fruits after 4 years already. The fruits are green at first, and become dark brown upon ripening. The tree can be pruned and kept small, when preferred. The wood is popular for furniture making.

Sowing instructions: Soak the seeds for 24 hours in water. Sow them in sowing mix and put away for 3-4 months in the fridge. Keep the soil constantly moist by covering it with foil or glass. Take the seeds out of the fridge and let them germinate at room temperature. Germination can take a long time, and sometimes another cold period is needed to break the seed dormancy. Germination can follow as long as the seeds are firm.   

Sowing time: August - February
Difficulty: Challenge
Minimum temperature: -30 degrees Celsius