In 1648 the Prince-Archbishopric was transformed into the Duchy of Bremen, which was first ruled in personal union by the Swedish and from 1715 on by the Hanoverian Crown.

[2] As of February 2020, the council is composed of:[3] The Mayoress of Grünendeich is Inge Massow-Oltermann (FWG) since 2016.

The coat of arms of Grünendeich consists of a shield parted per fess into silver and green.

The upper, silver half is displaying a red-and-white-striped lighthouse with the gold, red-edged beacons reaching to the sides of the shield.

The bottom, green half is displaying two silver roses, representing the local fruit orchards.