In her teens she was brought up at the Swedish royal court as the future queen of King Charles XI of Sweden, her cousin.
Juliana was born in Eschwege to Frederick, Landgrave of Hesse-Eschwege (son of Maurice of Hesse-Kassel and his second wife, Juliane of Nassau-Siegen), and Eleonora Catherine, a Swedish princess.
Juliana's mother had caused a scandal in Sweden when she confessed to her husband that she had an affair with a French lute-player and actor, Beschon, and was expecting his child.
It is said that Eleonora was too embarrassed to return to the Swedish court, so she preferred to live in the palace in Eschwege, although she did visit Sweden.
In 1679, Juliana's cousin, King Charles, gave her his permission to marry her lover, who was given the title Baron von Lilienburg (Lilie's estate was named Lillienborg).