He undertook botanical excursions from 1792 to Heligoland and Neuwerk.
[3] The plant genus Flueggea from the family Phyllanthaceae is named in his honor.
[5] Johannes Flügge had been married to Karoline Auguste Preller since 1811.
[6] Their son August died on 3 December 1839 in the district of Schleswig.
A diary with entries on his trip to France, among other things, is in the library of the Botanical Garden in Hamburg.